Earlier quoted context omitted.
Which particular thing you consider inconvenient or even annoying? You can even install Google Play there. I see just one minor tradeoff - no face unlock.
Google OS-level integration is absent, and while Google Play Services can be installed, you're still missing things like Chromecast. Also, there's more manual configuration (although I don't remember exactly what, I've never used GrapheneOS). A lot of stuff you do get for free, but not all of it, and stuff that's been removed as a "feature" isn't always stuff that nobody wants.
The problem with Graphene is that some app publishers are absolute asshats, they think their app is "more secure" when they require the Google verification spiel, when it is the other way around.