swwiiiitttcchhhedd Can confirm. I went through the troubleshooting steps in https://discuss.grapheneos.org/d/8330-app-compatibility-with-grapheneos
I also disabled the Talkback system app (don't do this; this was just for testing) and rebooted, in case it was reacting to an accessibility app being present, and I get the same message.
Crash log: https://pastebin.com/raw/7dwJrFGF
The app shows a black screen upon launch. When you close it and re-open, a crash dialog is shown. If you dismiss that dialog, the app shows the message from the OP.
Edit: launches fine on stock PixelOS. Can go through the welcome wizard. I don't have an account there so can't test signing in. But I have to assume that that works on stock OS as well, as it's not blocking me in the first place.