IMHO Zulip is a great choice for text chat for teams for companies. In your case take a look at Movim, XMPP based, Movim can do blogs and more: https://movim.eu/

signal-cli software can do this without physical phone. https://github.com/AsamK/signal-cli/wiki/Linking-other-devices-(Provisioning)

Another way to try to fix dependency problems, including complicated ones that apt cannot solve, is to use the magnificent aptitude deb helper. If you have aptitude not installed you can possibly still install it with dpkg. Download aptitude deb file and the aptitude-common deb file and save them to disk. For example for Debian : https://packages.debian.org/trixie/aptitude With dpkg it is in dependency problems situations still possible to install new software. Maybe dpkg --force-all or something like that is needed.

Make sure to make backups of your valuable things first via a Linux live session.

After you have aptitude installed, try e.g. :

sudo aptitude update

or

sudo aptitude install ncdu (or install some other small program you didn’t have installed already)

It may already show a suggestion solution.

This is usually the recommended way to fix such dependency problems.

sudo apt-get -f install