No recommendation on my end, I'm afraid. That said, I wanted to make sure you were aware that you can get Play Store just fine on GrapheneOS, either via Play Store through Sandboxed Google Play, or a Play Store frontend like Aurora Store.
You don't have to give up your apps to use GrapheneOS. :)
If you'd like to use F-Droid exclusively for your own reasons, that's another story, although you should be aware that F-Droid has multiple issues that make it less than ideal security-wise: