I'm not sure about Roku. I brought up the Fire Stick because that's what I have, and you were asking about other streaming platforms, too. I suppose you could try loading something on your TV's browser and see if it works? It'd probably be super clunky but it would do until there's a dedicated app.

FWIW, if you have a Fire TV, Peertube seems to work in Silk. Well, mostly. I couldn't get thumbnails to play, but the video itself ran smoothly on its own page.