I find roku really ad heavy and it sent tons of traffic back to roku.com. Same for firetv.

Same for me. I had to quarantine my FireTV box with its own rules on my network to stop it from using all of my XFinity bandwidth for the month just doing nothing but maybe an hour of actual usage per day.

I've got a Roku on a TV in a spare room because it's the cheapest way to add airplay to a tv - I have it plugged in to a "smart" power bar that only provides power to the roku when the TV is turned on, so at least for the 99% of the time that the TV isn't turned on the roku isn't spamming my network.

I've never noticed ads on mine, but I basically just go immediately to Fubo or ESPN apps and that's all do with it. I don't watch much on TV other than live sports.

Exactly. If I wanted ads and surveillance I'd have just connected the smart TV directly to internet in the first place.