Been using graphene for a month now with play store enabled (there are like 3 apps I have with it but I need them for work shit). It's definitely awesome if you're fine with all the fdroid apps, which I personally am for almost everything.

Well, there's one downside, and that's some apps have inconsistent notifications. Push notifications rely heavily on google's firebase API which no apps on fdroid use. So it's a bit spotty sometimes. Telegram from fdroid works flawlessly for notifications, yet other apps don't for example. That's more of an fdroid issue though, not graphene. However if you plan on ditching the play store in general, you will be using fdroid and possibly run into that minor issue.