What do you use for a phone provider? I have a Pixel and want to run GrapheneOS, but I'm on Google Fi and believe I'll lose some functionality if I do so. Wondering what plan you use and how it's working for you

I use T-Mobile and phone calls, messages (SMS) and 5G data just work. Without Play Services, you will lose RCS probably. I haven't tested as I don't care about vendor-locked protocols. My suggestion would be to use Signal instead.