Like many others, I had issues with my Onn AndroidTV crashing regularly. Recently I was in the app store and I noticed there were two updates to System Apps - WebView and Android TV Services. Tongue firmly planted in cheek, I haven't had any crash issues since I installed those updates.
Don't know if its a fix or just coincidence, but figured I would share in case it might help someone.
It does seem like something has improved. First two weeks one crash / freeze a day or more. Now maybe one crash in the past two weeks. This is the same on two Onn UHD devices.