My suggestion: https://threema.com/en/products/work (hosted) or https://zulip.com/ (OSS self-hosted).
It's hard to find a decent service that ticks all the boxes but I do sincerely hope that the EU can support Matrix to bring it up to the standard that we all deserve.
Sadly, the US has done this to ourselves… all this arm twisting and strong-manning is coming home to roost.
It’s not clear that patchwork EU government back offices migrating off Teams will hurt US tech, but long term, in aggregate, this is going to be a headache for American tech.
EU can’t out innovate US tech, but they can make it harder to dominate their markets.
why not?
Okay not today but China was known as the cheap copier and is now the innovator.