But kind of defeats the purpose of Grpahene OS.

No, it doesn’t. The sandboxing ensures that the Google services have none of the broad access to the operating system they have on a normal Android. For example Google won’t get access to your location unless you explicitly give the permission.

On Android:

• Mastodon: Subway Tooter (the best one IMHO, UI takes getting used to but has features other clients not even dream of)
• Lemmy: still comparing clients