I have been using Graphene OS and I have several group chats going using the default messages app. As long as the other members have iPhones there is no issues. If any of the group is not on iPhone they cannot see my messages and I cannot see theirs in the group chat but the iPhones in the chat still work.
Is there some settings I am overlooking that can fix this?
I am on Comcast Business Mobile and using dual eSIM.
I appreciate any help.

    Teursu144 I believe I have read that if the phone number was ever used by an iPhone it is necessary to deregister the number with Apple.

      Teursu144 I had similar issues with the default messaging app when I used it. Now I use and recommend QUIK. The developer has been quite active the past couple months with updates. The latest update was just released 3 days ago. It also has some nice features and customizations. https://github.com/octoshrimpy/quik

        My phone number is deregistered with apple so thats not it.
        I tried quik, but when I use a messaging app other than the default, I can send messages in a group chat, but when someone replies it creates a new text thread that additionally has my number in it. If i reply in that thread it sends the text back to myself.
        The issue is still there where I can't group message with non-iPhones.

        Yes, I solved it by deregistering the number with google.
        I guess since I'm on a google pixel it was trying to send rcs to the other android phones or something, which wasn't working with GrapheneOS.
        I'm not sure how it got registered with google in the first place as I come from iPhone.

        On the other hand I'm still stuck using the default messaging app or it makes a new chat and messages myself in group chats.
        I'm guessing this has something to do with dual sim but I haven't found a solution yet.