Maritime4165 I was able to confirm yesterday that i can use the GOS Messages app in the User profile instead
Have you received a SMS with it? In a 2ndary User profile, notifications appear with "New message" text instead of your SMS text. Aside from that, the app works.
As for Google Messages, I have yet to try to get that working (and not sure I want to based on what I have read on this forum)...
You don't need to give it Internet access, can disable RCS, and use it without a Google account after initial selection. But it is as useless as GOS Messaging app in terms of notification content when you receive a SMS. May as well use GOS app.
If you find an app that works inside a 2ndary User Profile, shows SMS notifications on time, displays SMS content in notifications, and isn't SMS Organizer, please let me know I'd love to switch :P