When I was searching for the same answer, I concluded that Fastic is one of the best options, or a popular / arguably the most popular one
It’s been fantastic so far, but it crashes like every other day. It’s extremely infuriating but I don’t feel like switching at this point with the data I have. Running Android oxygen OS
Fast Habit. Simple, easy, not bloated with unnecessary things. The only thing is the widget on my iPhone went a little wonky sometimes (does it think I’m in a different time zone?) so I just didn’t use that part.