I have a fairly new ish Pixel phone, do you think I'll be able to go back if I don't like it?

Yeah, it is very easy, it's described here:

https://grapheneos.org/install/web#replacing-grapheneos-with...

Similar to GrapheneOS, Google also has a web installer (linked from the above section). Just in case you didn't know - both installing GrapheneOS and recovering the stock OS will remove all data as well.