Depends on the company.

If small enough, group chats will work just fine with less struggle and overhead.

If larger, possibly.

NextCloud may do much of what you need.

Small group, but we have communication all-around the place. Throughout different chat apps(telegram, WhatsApp, Microsoft teams with some clients, etc.). This is from legacy days when the team was small and number of projects/clients were few.

I mean the team is still relatively small (around 20) plus external stakeholders.

I will look into NextCloud, thx.