Jumped to GrapheneOS a few months ago. Works great. The keyboard was bad but you should install FUTO, as some other comments recommend.

My only issue with it has been a few apps not working correctly, and not the ones I expected. I did my research before hand and knew that my banking apps would work, thinking those would be the main challenge.

Turns out the bike-sharing system in my city, Madrid, won't work. I ended up installing Google Play services (that run sandboxed in Graphene, but still wanted to avoid), and it works sometimes, but mostly doesn't. I use these bikes a few times a week, so this is a major hassle, and I end up carrying my ancient iPhone with me sometimes just for this.

This and Trade Republic have been my only two problems. Happy otherwise, but do your research before switching, and don't assume only the apps you expect to be problematic will be.