I have stumbled upon really useful application on playstore and I'm wondering whether it is working on android tv. I'm currently away from home and I cannot test it myself. Playstore website says it is not compatible with my MI box 3 but maybe the apk could do the trick?
https://play.google.com/store/apps/details?id=com.agooday.skipads
Why don't you just use https://smartyoutubetv.github.io/ to get an ad-free experience?