Dude, my Steam Link and Steam Controllers are still in active use and get updates to this day. I even have 2 backup Steam Links - at the end they were selling them at 5€ per piece, and since i use it to stream pretty much everything to my TV, i got some in reserve.

I’m still on the first one, and one of the Controllers is now working with my Steam Deck out of the box.

I agree (a bit) on the Steam machines, those were pretty much a flop when seen as isolated device - but they laid the groundwork for the Deck.