Hello, most games still support only Ubuntu 18.04, and they don`t work in Ubuntu 20.04. When support for new Ubuntu will come?

First, 18.04 has, like every two-years LTS release, 5 year support (but upgraded to 10 years) so there's no hurry there. Second, why wouldn't they work on 20.04? This isn't Windows.

And lastly, testing takes time, only GOG knows when. Unless a blue one sees this (which is unlikely) you might be better off contacting them directly.

It looks like the installers do not work with 20.04. Most games should work even if some may need a library that was not needed for 18.04.