That really depends on your threat model. The app isn’t monitoring your activity or has imbedded trackers. It pulls content directly from YouTube’s CDN. All they (Google) know is your IP address, but nothing else. For 99.9% of people that’s totally ok.

There’s a flatpak too, but it’s not good.

Really? It’s been working just fine for me.

There are several way, honestly. For Android, there’s NewPipe. The app itself fetches the YouTube data. For PC, there are similar applications that do the same such FreeTube. Those are the solutions I recommend.

If you’re one of those, you can also host your own Invidious and/or Piped instances. But I like NewPipe and FeeTube better.

It doesn’t work for me, sadly. I hate timers and time blocking. What works for me is setting up reminders, and then doing things whenever I’ve mustered up the energy to; it’s been proven to be pretty efficient so far. I will always do that - unless there’s something that I absolutely need to set up a timer for, or time block. That usually includes meetings or working on a project with someone else.