And AFAIK they have only been desiring to build their own RCS app, and researching it, but have no concrete plans. It'll probably be extremely hard to do, given how much interaction it requires with individual telecoms, and how large the specs are and how much they change - it'll be signing up for significant dedicated eng/business/etc effort that will never decrease. Though I would very much like it if it does happen.
Personally: it worked for about a year for me, then stopped for several months, then worked for two, then I disabled it. All on the same phone, same OS install, same carrier and phone plan, and same location. No issues at all on stock Android with everything else identical which my wife uses. You can find tons of cases like this with Graphene users, RCS just doesn't work/activate/??? as well for some reason.
I'll definitely be curious about the source code when that happens, and if it'd be reasonable to get it into a SMS-provider-like shape eventually. Particularly since Android's original PoC did that, but it was abandoned for some reason.
I had installed graphene os on a pixel but after a couple months and a couple loops between lineage, stock, and graphene, I eventually settled on stock android. I have group messages with family and some of the family are on apple, some on android, and RCS only works with google messages and google services installed.
It's infuriating that I can't send RCS messages unless google allows me to. I want to go back to email or MMS. Supposedly after a month (!!) RCS group chats will fall back to MMS, but that was not my experience. Also, if you turn RCS on/off you may get kicked out of group messages [0].
[0] https://support.google.com/messages/answer/7189714?hl=en
Initially there were some promising details planned, but much of it hasn't panned out, and plus now it's Just Google™. Like, roughly everyone has heard that RCS brings E2EE privacy, right? Would it surprise you to learn that it was only added to the spec around a year ago, and nobody has it implemented yet? Google has their own thing between Google users, Apple has their own iMessage-only thing, and they both drop crypto when you cross the streams because it isn't in the spec. And neither is practically auditable (allowing auditing is part of the spec btw - have you seen that UI?).
And that's before even touching on the utterly massive amount of the spec that's clearly designed for businesses only, to send you highly customizable interactive UI. Which you can't use as a person. Or build your own app for. https://developers.google.com/business-communications/rcs-bu... / https://rcsforbusiness.google/
It just does not smell good. It's not in our best interests to let it win.
Unfortunately Google revived it but it's a very poor standard for interoperability. Not only because the lack of true E2EE in the open spec but also because you need to be a blessed party to run an RCS server and communicate with others. You can't run your own or choose a party you trust. It's either your carrier if they bother to run one, or Google.
It's just another power grab. Don't fall for its 'open' guise. They want you to use it so they can make you dependent and lock you in again. There's nothing open about it. If you want privacy, use signal. If you also want an open and federated network, use matrix or xmpp with OMEMO.
I strongly disagree with this negative characterization. RCS was a replacement protocol for the extremely outdated SMS and MMS protocols. Apple only supported SMS/MMS chat with Android users in iMessage, which meant that cross-platform chats were strongly limited in many ways (e.g. the mentioned emoji reacts), which caused many US American kids to be socially punished for having an Android phone, which is likely part of the reason why Apple is so dominant in the US now, especially among younger users. (Other countries mostly don't use iMessage/SMS, but something like WhatsApp, so they never had this problem.)
RCS was the solution to these iMessage/SMS/MMS incompatibilities. It took years for Google to convince Apple to adopt it, and Apple only announced doing so after EU regulations were on the horizon. There were even internal emails which revealed that Apple used their iMessage dominance and the poor Android compatibility via SMS/MMS to boost their market share in the US.
In summary, RCS is great because it is both a modern chat protocol, unlike SMS and MMS, and an open standard, unlike the closed iMessage and WhatsApp protocols, and available cross platform, unlike iMessage.
But that would mean that the entire protocol would have to be made open including E2EE, and that other parties besides Google and the telcos would be allowed to run servers. Those things are very unlikely to happen.
And the social problems are not a technology problem, it's more a result of the harsh competitive American society. Without blue bubbles there'll be something else that kids will be bullied for. Only when the whole concept of "everyone except the #1 winner is a loser" is dropped this will disappear.
And Google didn't try to convince Apple to do this out of the goodness of their heart. Like I said most of the protocol (except the E2EE) is open but the implementation is not. It gives google even more control. You also won't be able to use it on a PC without a google account which is a big dealbreaker compared to Whatsapp and Signal. iMessage isn't a thing here in Europe anyway (neither is SMS/MMS).