Of course you can't use Youtube? Its a Google product. Its built ground up to depend on Play Services.
That being said Youtubes mobile site isn't abysmal and I'm not a fan of how the last decade saw the open web replaced by proprietary apps. A lot of sites work fine in a browser on a phone but still push users to use an application to interact with them.
FireOS on my Kindle Fire is still at Android version 5. Fortunately, I was able to install Google Play Services so that I didn't have to use the Amazon AppStore, however multiple profiles doesn't work well on the Kindle Fire. F-Droid is pretty awesome and the ADB toolset is pretty powerful too. I'd love to find a wrapper that just uses the core Android tools for management.
That being said Youtubes mobile site isn't abysmal and I'm not a fan of how the last decade saw the open web replaced by proprietary apps. A lot of sites work fine in a browser on a phone but still push users to use an application to interact with them.