Lisen or read. They have this as an automatic response. I reported split screen coop issue at October 8.
Video as proof. I got the same reply like you Nyloth. Did they fix it? No The broke it on every other platform as well. From patch 3 BG3 isn't considered as feature complite. Because split screen is a main feature. FOR THE NINE HELLS The entire reason it's not on Xbox right now. Do they really care? No because we got 4 hotfixes after that 1 major patch note what breaked multiple things. Like act 3 laag textures not loading stutter SteamDeck not working. And lot of other things. But those things are major features. Especially that on SteamDeck the game is not running at all.
Yes some of the community members gived some workaround for the steam deck. But if you use them , then you can't play multiplayer at all. So both way" feature complite" is a lvl 7 illusion spell that is not existing in this game.
So yes definitely we need better support and communication.