I just managed to run the whole thing on a pi (moved the thing over to an INTEL NUC now, since my heavy use of PI cpus & SDcards keeps burning them out), so I would assume that you could get away with hosting the whole thing on a cheap 5 dollar DigitalOcean (or something local to you with comparable prices) server and have a few hundered people connecting to your room without too many problems.

Room V1 was running on a pi4 for a year and saw 70 people connecting to it at the same time from time to time without breaking a sweat.
That while running my aurora-bot, my personal marvin voice assistant backend and a bunch of random sites & projects)

Rooms V2 runs on rust which compiles straight down to C, so it "should" be faster and lighter even ;)

If you do go with Digital ocean you could use this dirty trick to get some extra ram
https://gist.github.com/hendrikpetertje/7986434
(I tend to inject about the same amount of already allocated RAM into swap)

I can not recommend this if you do this on your own private physically owned SSD or a raspberry pi SD card.