To answer the last part of your post:

So far my experience is that the RCS-iMessage feature is working (or not) depending on the Apple user’s provider. I’m on Android with a “cheap” provider in Canada and RCS-iMessage work with my iMessage contacts that are on major providers but those on cheaper providers don’t work yet.

So if you are on Android and your basic RCS works you should be good.

S’ils ne sont pas géographiquement bloqués en France vous pouvez utiliser ceux du CIRA. Ils ne devraient pas être censurés. Reste à voir la latence transatlantique.

https://www.cira.ca/fr/bouclier-canadien-de-cira/configure/summary-cira-canadian-shield-dns-resolver-addresses-2/