Do any unlocked Samsung phones actually work with XM??

I'd really like to take advantage of one of Samsung's Black Friday deals on either the Galaxy A51, or A71 unlocked and then sign up for XM, but although they claim to take "most Samsung phones" it seems that this is wildly innacurate. What is the deal?  Does Xfinity support these phones or not?  What could possibly be the reason that buying one for twice the price from Xfinity works but an unlocked one from Samsung doesn't.  Isn't it the same darn phone?? 

Can anyone answer if either of these could work, or have worked, or do I just have to wait for XM to expand their catalogue of supported phones? 

PS -Does anyone at XM even know definitively what phones work on their network?  It seems no one is really sure.  Pretty crazy in a sad way.