I can confirm that the second workaround did the trick for me. (Unlike the first).
First I changed "/etc/apt/sources.list.d/debian.list"
# Debian Stable.
deb
http://deb.debian.org/debian bookworm main contrib non-free non-free-firmware
deb
http://security.debian.org/debian-security bookworm-security main contrib non-free non-free-firmware
#deb-src
http://deb.debian.org/debian bookworm main contrib non-free non-free-firmware
#debian backports
#deb
http://deb.debian.org/debian bookworm-backports main contrib non-free non-free-firmware
-->> temporarily for activating chromium <<--
deb
http://ftp.us.debian.org/debian bookworm-proposed-updates main
Then save /etc/apt/sources.list.d/debian.list/debian.list
-- In the terminal
sudo su
...
root@<computerName>:/home/<user># apt update
Get:1
http://security.debian.org/debian-security bookworm-security InRelease [48.0 kB]
Hit:2
http://deb.debian.org/debian bookworm-updates InRelease
Hit:3
http://deb.debian.org/debian bookworm InRelease
Hit:4
http://nl.mxrepo.com/mx/repo bookworm InRelease
Hit:5
https://repo.nordvpn.com/deb/nordvpn/debian stable InRelease
Get:6
http://ftp.us.debian.org/debian bookworm-proposed-updates InRelease [60.6 kB]
Get:7
http://ftp.us.debian.org/debian bookworm-proposed-updates/main amd64 Packages [72.7 kB]
Get:8
http://ftp.us.debian.org/debian bookworm-proposed-updates/main i386 Packages [70.9 kB]
Get:9
http://ftp.us.debian.org/debian bookworm-proposed-updates/main Translation-en [47.9 kB]
Get:10
http://ftp.us.debian.org/debian bookworm-proposed-updates/main i386 Contents (deb) [467 kB]
Get:11
http://ftp.us.debian.org/debian bookworm-proposed-updates/main all Contents (deb) [527 kB]
Get:12
http://ftp.us.debian.org/debian bookworm-proposed-updates/main amd64 Contents (deb) [410 kB]
Fetched 1,704 kB in 2s (941 kB/s)
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
7 packages can be upgraded. Run 'apt list --upgradable' to see them.
Those 7 packages ( libglib2.0-0, libglib2.0-bin, libglib2.0-data, libmariadb3, libsrt1.5-gnutls, libsynctex2, mariadb-common) are not needed for the chromium install so I ignored them.
root@<computerName>:/home/<user># apt install chromium
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following additional packages will be installed:
chromium-common libc++1-19 libc++abi1-19 libharfbuzz-subset0 libminizip1 libunwind-19
Suggested packages:
chromium-l10n chromium-shell chromium-driver clang
Recommended packages:
chromium-sandbox system-config-printer
The following NEW packages will be installed:
chromium chromium-common libc++1-19 libc++abi1-19 libharfbuzz-subset0 libminizip1 libunwind-19
0 upgraded, 7 newly installed, 0 to remove and 7 not upgraded.
Need to get 95.5 MB/97.5 MB of archives.
After this operation, 325 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1
http://security.debian.org/debian-security bookworm-security/main amd64 chromium-common amd64 131.0.6778.108-1~deb12u1 [10.2 MB]
Get:2
http://ftp.us.debian.org/debian bookworm-proposed-updates/main amd64 libunwind-19 amd64 1:19.1.4-1~deb12u1 [62.6 kB]
Get:3
http://security.debian.org/debian-security bookworm-security/main amd64 chromium amd64 131.0.6778.108-1~deb12u1 [84.9 MB]
Get:4
http://ftp.us.debian.org/debian bookworm-proposed-updates/main amd64 libc++abi1-19 amd64 1:19.1.4-1~deb12u1 [104 kB]
Get:5
http://ftp.us.debian.org/debian bookworm-proposed-updates/main amd64 libc++1-19 amd64 1:19.1.4-1~deb12u1 [301 kB]
Fetched 95.5 MB in 4s (23.5 MB/s)
(dpkg-preconfigure:5135): dbind-WARNING **: 17:19:56.793: AT-SPI: Error retrieving accessibility bus address: org.freedesktop.DBus.Error.ServiceUnknown: The name org.a11y.Bus was not provided by any .service files
(dpkg-preconfigure:5133): dbind-WARNING **: 17:19:56.858: AT-SPI: Error retrieving accessibility bus address: org.freedesktop.DBus.Error.ServiceUnknown: The name org.a11y.Bus was not provided by any .service files
Selecting previously unselected package libunwind-19:amd64.
(Reading database ... 279569 files and directories currently installed.)
Preparing to unpack .../0-libunwind-19_1%3a19.1.4-1~deb12u1_amd64.deb ...
Unpacking libunwind-19:amd64 (1:19.1.4-1~deb12u1) ...
Selecting previously unselected package libc++abi1-19:amd64.
Preparing to unpack .../1-libc++abi1-19_1%3a19.1.4-1~deb12u1_amd64.deb ...
Unpacking libc++abi1-19:amd64 (1:19.1.4-1~deb12u1) ...
Selecting previously unselected package libc++1-19:amd64.
Preparing to unpack .../2-libc++1-19_1%3a19.1.4-1~deb12u1_amd64.deb ...
Unpacking libc++1-19:amd64 (1:19.1.4-1~deb12u1) ...
Selecting previously unselected package libharfbuzz-subset0:amd64.
Preparing to unpack .../3-libharfbuzz-subset0_6.0.0+dfsg-3_amd64.deb ...
Unpacking libharfbuzz-subset0:amd64 (6.0.0+dfsg-3) ...
Selecting previously unselected package libminizip1:amd64.
Preparing to unpack .../4-libminizip1_1.1-8+deb12u1_amd64.deb ...
Unpacking libminizip1:amd64 (1.1-8+deb12u1) ...
Selecting previously unselected package chromium-common.
Preparing to unpack .../5-chromium-common_131.0.6778.108-1~deb12u1_amd64.deb ...
Unpacking chromium-common (131.0.6778.108-1~deb12u1) ...
Selecting previously unselected package chromium.
Preparing to unpack .../6-chromium_131.0.6778.108-1~deb12u1_amd64.deb ...
Unpacking chromium (131.0.6778.108-1~deb12u1) ...
Setting up libunwind-19:amd64 (1:19.1.4-1~deb12u1) ...
Setting up libminizip1:amd64 (1.1-8+deb12u1) ...
Setting up libc++abi1-19:amd64 (1:19.1.4-1~deb12u1) ...
Setting up libc++1-19:amd64 (1:19.1.4-1~deb12u1) ...
Setting up libharfbuzz-subset0:amd64 (6.0.0+dfsg-3) ...
Setting up chromium-common (131.0.6778.108-1~deb12u1) ...
Setting up chromium (131.0.6778.108-1~deb12u1) ...
Processing triggers for desktop-file-utils (0.26-1) ...
Processing triggers for hicolor-icon-theme (0.17-2) ...
Processing triggers for gnome-menus (3.36.0-1.1) ...
Processing triggers for libc-bin (2.36-9+deb12u9) ...
Processing triggers for man-db (2.11.2-2) ...
Processing triggers for mailcap (3.70+nmu1) ...
I unelegantly removed all At and At-SPi shite from my system, so the errors on (dpkg-preconfigure:*): dbind-WARNING can be ignored.
The I changed "/etc/apt/sources.list.d/debian.list"
-->> temporarily for activating chromium <<--
deb
http://ftp.us.debian.org/debian bookworm-proposed-updates main
to
# install succesful ! -->>
## deb
http://ftp.us.debian.org/debian bookworm-proposed-updates main
The I saved "/etc/apt/sources.list.d/debian.list"
-- In the terminal
root@<computerName>:/home/<user># apt update
Hit:1
http://deb.debian.org/debian bookworm-updates InRelease
Hit:2
http://security.debian.org/debian-security bookworm-security InRelease
Hit:3
http://deb.debian.org/debian bookworm InRelease
Hit:4
http://nl.mxrepo.com/mx/repo bookworm InRelease
Hit:5
https://repo.nordvpn.com/deb/nordvpn/debian stable InRelease
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
All packages are up to date.
--->> But <<<---
chromium wasn't starting (even after reboot)
-->> So <<--
I also had to install chromium-sandbox
which I did with synaptic.
Then chromium was back again (:-)