VRchat is a great example. There is also Altspace VR. Though that is PC only. Pavlov VR is an fps but some of the maps are experimental and interesting.

The most cost effective way to get started is a quest 2. With a link cable you can use it as a pcvr headset as well.

It does however require a Facebook account.

One place you can look for some of the more unusual content on the quest is https://sidequestvr.com/