I believe they’ve (Google) been somewhat successful in convincing carriers / 3rd party OS devs like Samsung to start implementing RCS in their own messaging apps. There’s even a 3rd party app on iOS that can use it now.

Check out the XDA Forums section for your carrier’s version of whatever model of phone you have. Not all carriers make it trivial (or even possible) to unlock the bootloader and flash custom recovery images, but if it’s possible then someone there has certainly done it.

RCS is our last hope…

No, in so far as its a valid community to link to considering this is beehaw (not federated with a few large instances) and it’s 100% relevant to the thread they posted it in.

I mean it’s quite literally not, but whether it’s tasteful to link to a different community is up to personal choice I guess.

I would say, do a decently deep dive into your model’s section on the XDA forums. The people over there are the go to for rooting and custom recovery flashing.

The reason I think this is super important, is because the fact that you haven’t found a specific guide for the 3 Strix might possibly be that it just isn’t supported yet (or may not be possible to support). I used to have similar issues with certain carrier-specific models not actually supporting the steps needed to flash TWRP over adb or even unlock the bootloader period.