Can lidar be purchased for hobbyist use yet?

Depends on your budget and the resolution you need.

E.g Livox mid 360 https://store.dji.com/en/product/livox-mid-360

I haven’t done it myself but I’ve heard of people harvesting LiDAR units from their old/broken robot vacuums.

Check out PiLIDAR for one of many options:

https://github.com/PiLiDAR/PiLiDAR