You want Matrix. Synapse if you intend to host for others, Conduit if you just want to host for yourself. There are quite a few different clients but I do indeed use ElementX on mobile.

There is an extremely arbitrary distinction made between the USA and Russia.

Your world view seems to be highly influenced by propaganda. It’s very easy to draw a distinction between these two countries. Let me start with an easy one:

Russia is a dictatorship, the US is a democracy.

If you were just selfhosting services for you and your family, would really browsers be flagging your site?