Ad-Guard: Works very well, including ability to block YouTube ads.
LastPass: A password manager, useful for cross platform password storing.
PiPifier: Enables PiP in any video player.
Tab Suspender: Suspends tabs after a period of inactivity. Helps with websites that tend to use resources in the backgroud.
Ad guard: download the app and integrate it as a content blocker in safari options. I’ve been using it for a long time. It offers a lot of features.
Password managers: can also be integrated in the OS itself by installing the app and set the config.
To be honest, since I stopped using a Windows machine I almost completely switched to Apple's own keychain. That said, I still have the LastPass because it is easier to use for storing private data that does not strictly conforms to the "username and password" convention.
On my script and on the Pipifier, YouTube would stop playback when you lock the device but you can resume it through tapping the play button in the control center.