I have a quest 2, mainly I play Beat Saber (~$20 if I remember correctly, though it’s a really good investment and a really fun game), Gorilla Tag, Rec Room, SUPERHOT VR (also around $20 if I remember correctly, however this is arguably more fun than Beat Saber), and Arkio, which isn’t really a game but is still fun. YouTube VR is also kind of fun sometimes. As for things like Sidequest, I’ve only tried sideloading Minecraft VR, which was a very silly experience, however I would not recommend playing MCVR for longer periods of time because it gets very tiring and it’s pretty buggy.

plenty of things on sidequest as several thousand ppl will tell you (first things that spring to mind are half life and doom ports)

gorilla tag (as long as you dont mind being screamed at by 2 year olds)

population one - free vr battle royale

rec room - you (probably) know what rec room is

roblox - see above

Not free nor cheap, but Bonelab is the best game for oculus

sidequest, though im pretty sure you already know about that