I was thinking that there should be a steam auth login button so people can sign in though steam. would it be a good idea?
It’s entirely possible to do that and there’s a lot of discussions in the forum about “how do I add login via [pick some service]”. What’s sort of interesting about Steam is it’s not your typical Oauth type login system. From a very quick glance, Steam authorization uses a system called OpenID. Looks like the reason for this has to do with age verification, etc. (of course, many Steam users are minors).
Very brief info on Steam auth:
which quickly leads you to:
It doesn’t look super easy/straightforward to implement Steam user authentication, but I’m sure one could eventually figure it out with a little poking around. (Given the complexity, I’d assume there must be a good number of stackexchange/stackoverflow threads about how to do this!)