Pixelpioneer88
If you want reason for hope, the new RCS 3.0 standard (not yet in use by anyone, so far as I know) is intended to facilitate cross-platform, cross-vendor interoperability. It's endorsed by the GSM industry association and Apple. I suspect Google will not try to 'pull an Apple move' and stay with what is presently akin to a proprietary Google RCS implementation, but 3.0 is new, and it's anyone's guess as to when Google will support it or whether they make it part of AOSP for GOS to work from. If it's not to be part of AOSP, then it's a harder road for GOS to get the stock messenger compliant, but it's not impossible that other messengers begin to support the 3.0 standard. I certainly hope so as there are significant limitations (and frustrating issues with using Profiles) to the stock GOS messenger. I can't make my world use Signal, so I'm holding out hope that this will somehow get addressed, but it's not looking hopeful this year.
See my post (#572) for more info on RCS 3.0:
https://discuss.grapheneos.org/d/1353-using-rcs-with-google-messages-on-grapheneos/597