hiho SLF, welcome!
the lobby used to be visible via
https://tfe.gg/lobbies which is a community made page
but i think it broke on one of the patches. i guess it will be back up at some point.
i think this is the best indicator at the moment:
https://steamcharts.com/app/1148810
sometimes useful to be on their Discord
https://discord.com/invite/d6HhVwq to see if ppl are going online or to get a feel of how things are going.
you might find your time zone is lucky or not. I've not been on for a bit but there used to be active EU server until late EU time, then US server would be popular.
you have any friends playing or were part of any clans in the past? i think you will get the DF feeling from the game, and it's cheap because it's still early access. but it's who you are playing with that counts more often than not.