I recently discovered SmartTube Next for Android TV to get an ad free experience and integrated Sponsorblock on my Nvidia Shield TV.
I found NewPipe for my phone but I don’t see a way to connect my YouTube account to it and I guess I need to import my subs manually every time I change something.
So I’m wondering if there is an alternative YouTube app that is blocking ads (and ideally integrates Sponsorblock) for my smartphone and has the ability to connect my YouTube account like SmartTube Next does?
GrayJay is not free. It is just a paid app that you can use without paying.
If it is free to download, free to use and has no pay nagging or restrictions then it is effectively free to any user. As I said, you can buy a license to support its development and this is clearly what they would like you to do, but there is nothing forcing you to pay.
The difference is that you are expected to pay. Louis and FUTO are very explicit about this.