Moi? I use currently a NOTE 20 ultra 5g. Probably my second best phone, I only hate the fact it’s so massive (I miss being able to use just one hand for my phone) and the mediocre battery life for someone like me that watches a lot of videos. But the S pen is so handy those few times you need it.
It’s very easy to install GrapheneOS. All the instructions are laid out on their site. There are two options CLI or a web installer.