So then what's the point of having a Play Store without Google Play services?
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.
Install Droidify, enable the repos, and install "microG Services" and "microG Companion".
I am personally more than okay with using the official, proprietary GP services from time to time if they abide by the same rules, especially that I can make these rules as strict as I want.
And even if you install Google play on your graphene phone, it is still more isolated by default. Add that to the concept of storage scopes and more permissions control (apps have to ask for access to the network) and you have a more secure platform.
No thanks; I choose to forego Too Good To Go instead of that. They are the only truly broken app I have found.