Many apps claim to require Play Services, but all my (several) bank apps work perfectly on GrapheneOS. No notifications because they rely on Google, but that is more feature than bug in my books.

Signal brings its own notifications, so they work perfectly.

The only app which was broken to the point of unusability was Too Good To Go, which demands that you pick locations on a map which relies on Play Services; the manual city entry is broken.

I use Google Maps only in Firefox Focus, but I've heard that builds of Google Maps up to about a year or so ago didn't rely on Play Services, and with Aurora Store you can manually enter a build number to install.

tl;dr: 10/10, fabulous experience.

Need the Maps data, the satellite picture, or StreetView? All these past years this WebView wrapper have been working like a charm https://f-droid.org/packages/us.spotco.maps

Uh GF uses TooGoodToGo, I might try if it works with MicroG and the companion app which appears at FDroid (can't recall now the name, but it appeared with Droidify and some repos). It must be a Play Services API placeholder out there too.

Install Droidify, enable the repos, and install "microG Services" and "microG Companion".