Hey Alexandr!
As you have mentioned above, angular forms look abandoned. Error messages should be a part of the original API and we should not need to implement our solutions for this. My solution works well but it has some important points to fix.
It checks for all form controls even when only one change.
It does not end the subscription which may cause memory leaks.

So, yes it works but it is a little expensive.
I would be very happy to discuss with you what type of solution you have found for this and ways to improve my and your solution.

Please contact me on Linkedin or Twitter or email.
Linkedin, Twitter, klementomeri97@gmail.com