Yes, Ring Fit Adventure works with Switch Lite. Obviously, there are some caveats with the experience. You'll need a separate pair of Joy-Con to actually connect with the Ring-Con and leg strap. Also, the Switch Lite doesn't have a kickstand, so you'll have to find a way to prop the system up. As long as you're okay with those two things, you can play on without issue.
Not the best way to play, but it'll do