>>296212308
Display.land is the easiest to use, if you have a phone that supports their app. about 5 minutes of walking around with your phone, an hour of processing on their end, you get back a downloadable mesh and texture that you can import straight into unity.
https://www.display.land/s/4q1m0dHYSX0vHdsAEfDfge
Very blobby, but has its charm.
>>296215139
I haven't tried meshroom myself beyond small scans but I think it's more in the realm to 1000s of images for good room scans, not 100s, and it'll take hours to process into a mesh even with a good gpu. It is free though, so if you have the time to snap a few thousand pictures with neutral, similar lighting, go for it.

If you have a kinect, there's also a way to do 3d scans with that, though I don't know the exact process.

In either case (meshroom or display.land), I wouldn't expect great results the first time. I took a few tries to get a decent scan, and even then there's a technique to getting the right shots and angles for 3d reconstruction and good textures. Try a small area first, then expand.