Are there any apps that support RCS that aren't made by Google or a crappy cellular provider (ie: bloatware Verizon apps)?
I appreciate the features RCS has, but I'd love to get that without sending it all to Google with a "trust us" approach to backdoor keys. The documentation I looked at indicated that anyone could setup an app to support RCS and communicate with Google's RCS users, but I can't find any apps that actually do that.
Also would love to be able to message from multiple devices using RCS, which Google has working in their web app.
RCS is all about controlling the messaging market — just like every other messaging network out there. Every implementation is proprietary and locked behind the implementer's servers.
If you want something open source you want Signal. There are also other messaging solutions that you can self-host.
Big tech will never give you open access to their networks because that's against the whole point.
SMS is the odd one out because it doesn't require servers, and the reason it's so open and universally supported is because back in the day the governments of France and Germany forced carriers to do it that way, and once it got popular it spread.
Correct me if I'm wrong, but to my understanding of how RCS works, the messages would still go through Google and their servers. With that said, this would probably be more privacy friendly than straight up using the Google Messages app, since it'd have less Google telemetry and data collection, but still not ideal or truly private since it'd still be Google's platform you're using to message at the end of the day.