Chromium is the open source project behind Chrome. It’s not generally intended for downloading to install for end users (except Linux where it’s often packed up instead of the full Chrome on the more open source distributions).
Shouldn’t be anything dodgy with it, though it could have been packaged by a dodgy download site with lots of junk.
Anyway, Defender is generally fine enough, but it doesn’t deal with adware, nagware and just generally badly written software that doesn’t uninstall properly (*cough* McAfee *cough*).
Defender + some common sense on what you download and careful check on where you are downloading from + occasional use of MalwareBytes.