[gnulinux]

Same for me. I started very recently but it improved my productivity very sharply (not just work, also hobbies (music) and cleaning). I use habitica (no affiliation).

[xenodium]

I built and use https://flathabits.com daily.

Keeping habits and todo/tasks list separately helps me prevent the latter from monopolizing habit time.

ps. Flat Habits is backed by org (if that's important to you), but this is purely an internal detail if you just want a simple app.