This is a plugin I found recently and really enjoy. It gives you the opportunity to redirect several webpages to alternatives. For example Youtube to FreeTube or Piped. If I search for youtube in Firefox, FreeTube automatically opens and shows me my feed. I like it, I use it, I can recommend it.
Only the first and maybe second gen is like that. If you get a current one with Google TV, or any Android TV box for thar matter, you can install any apk you want. Either through its special store or by sideloading with a browser or ftp or whatever you want
Well I am using a Chromecast Ultra, but who knows.