>>81247202Bunpro (grammar) and jpdb (vocab) both track streaks. You could use a separate app or stickers on a calendar if you're doing something else, though.
Also like
>>81247270 said, Satori Reader is very good, but I wouldn't start it til you're at least comfortably N4. The company that makes it also does an app called Human Japanese for absolute beginners that I highly recommend