Yes they do…at least in some fashion. I have a smart ir blaster I got off Amazon. Broadlink. It has connect to Siri option in their app. I can create a shortcut voice command to turn on or off any item I have programmed in in their app. It lacks other controls like change temp or channel etc, but for most devices I have, I just want to turn on or off via voice, it works fine to say Hey Siri, turn on/off xyz. It does not support homekit btw.
So far, it does seem overall, Apple is much more limited in the smart home venue compared to competitors. To this I was not aware until I started to use iOS a bit.