I was wondering if there is any way (app or something) to bruteforce app login forms on Android?
Yes. You definitely can do this, but it would be easier to bruteforce the actual service. For example programmatically generating login requests and send them manually to the authentication service to which the app is communicating.
Bruteforcing login forms of android apps directly would be much slower, but still be possible. You probably need to get higher privileges on the app performing the bruteforce to automate the UI interaction events from another app.