Karsten

KDE Connect is an app to connect your phone and computer. It works on most OS (windows, Linux, etc.), and it works extremely well (better than the solution developed by Microsoft).

KeePass is really good, but it definitely requires to handle everything outside the password management (like syncronization between devices, TOTP, password quality check, etc.). It is not user friendly at all. Thankfully KeePassDX (on Android, not pc) has a way better built-in experience.

For YouTube, check out newpipe on F-Droid. No ads, you can download content, play videos in background, etc.

Yes. I've been using almost daily and it's great! My only issue is that it sometimes (like once every one or two months), it has some trouble connecting back to my phone.