I used MLB.tv all year on my Shield, but with football coming, I was looking for something similar. Living on my own now, I don't have cable and have done my best avoiding needing it. MLB.tv has worked flawlessly for me and love using it.
Is Sunday Ticket my next move for football? How's the quality and is it fully supported by the Shield TV?
I just singed up for DAZN. Currently on their 1month free promo, but I'm loving it so far. https://www.dazn.com it's great the shield TV
I would take a look at the /r/cordcutters guide for watching NFL games . There's more options than just Sunday Ticket.
It doesn't work with AndroidTV, I don't know why they list it. Maybe because it can be casted from a phone app, but that's the only way it works.
Worst case scenario just view on phone and cast it. I tried that last season and it was great.
If you are steaming NFL and NHL go and get yourself a Ruko. They have all the app you need. sometimes when you slideload apps on Android TV they don't work that good. Example is NFL game pass always locks up on me after a few minutes but the roku I never have issues .
Note Roku Stream the best IMO however they don't have apps for IPTV and they are slower with a ugly GUI. I do wish Roku would allow the perfect player app
Should be fully supported natively.
Supported platforms