I really can’t believe that chat control will come. But also I was wrong before and strange things happen… So there are applications that can’t really be considert providers of chat services. Like: Deltachat, Element, Conversations or Silence. Which use the protocol’s Email, Matrix, XMPP, SMS for which there are numerous providers. Therefore allowing you to simply send E2E messages without the provider having any influence.
U might want to take a look at the federation map. It might be a bit overwhelming but in the settings on the bottom left you may chose blocked and allowed in order to get some insights on who federates with whom.