Hi, I don't think there are VPS optimized for Flarum: a VPS is just a Virtual Private Server and maybe more then optimization we could talk about how much resources a VPS should have... but I think also this depends by various factor like how you want use VPS, how much big the Flarum community would be, etc.
Maybe you can consider a VPS that allow you to upgrade resources if they are not enough or just start with a good VPS that has good CPU and RAM.
