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.
Unfortunately both ReVanced and ReVanced Extended do not support casting. Just tested it. The whole issue is that I need it put onto the TV, which they unfortunately can not do. I will be keeping them for when I am watching on my phone, so thank you for that.