App looks legitimately amazing. Seems a bit buggy in alpha but I'm sure it'll be ironed out. I just hope they look into supporting Piped instead of directly connecting to YouTube, as well as SponsorBlock. Once they get those 2 things and iron out some of the bugs, I'll primarily use it for sure. Its a great concept.
Yeah, Shizuku opens up a massive attack surface through ADB. ADB can do a lot to your device without you even realizing it in a lot of cases, and you're basically giving ADB access to Shizuku itself and any apps that use it (which could be exploited) at all times, so its very risky. Its pretty dangerous and definitely best to avoid an app like this.