Hi there. Keep in mind that, unlike stock android, GrapheneOS does not compromise your privacy by default. Nothing you find installed by default is harmful in any way, so many of the points listed in the video are not applicable. Don't alter the permissions of default apps, you gain practically nothing and are bound to break something.
mtee Second, even with permissions turned off on many apps...I just don't know if I trust/believe it.
Respecting permissions isn't done voluntarily, it's not done on a good-will basis. Apps can't access data you haven't permitted them, you would need to burn expensive exploits for this to happen.
mtee Concerns - General app compatibility concerns
Substantial efforts have been made to preserve app compatibility, the vast majority of apps work without a hitch thanks to sandboxed google play, toggles like exploit protection compatibility mode and the likes. Banking apps can be problematic, see this thread for troubleshooting steps and the community maintained privsec list for user reports.
mtee Phone support concern - I heard Graphene follows the Google schedule.
Yes, the security patches have to come from somewhere, that includes driver and firmware updates. There are extended support releases done on best effort basis available for older devices but they can no longer be considered (fully) secure.
mtee Concern is that with a smaller network company + a less common OS is going to be a bad combination and lead to a basic functionality issues.
See this for details but carrier functionality isn't a big concern.