For starters, I don't think you understand how much of a downgrade most phones are to a Steam Deck. Also, if it works on your Steam Deck, what's the big issue? Playing on a phone is horrible. You'll have a way better time on your Steam Deck. Plus, this doesn't really go against my argument. The overall experience will be better, smoother, and faster on a PC. You can just say, I want to be able to play it whilst moving around. I don't want to be locked on a PC, that's fine. But at that point, you might as well just play it on your Steam Deck.
You understand you can play Vintage Story on the phone? Id understand if you dont like playing games on the phone, but thats not really an excuse to say it shouldnt be on the phone. Minecraft is on the phone? PUPG is on the phone? the new Resident Evil 4 remake is even on the phone? You can get attachments if you dont like touch screen controls. Furthermore, my phone can fit in my pocket, my Steam Deck cant. And its not that much of a downgrade, be forreal, there's even phones built for gaming nowadays. So, realistically, you can play Vintage Story on your phone, it'll run fine on your phone, and it wouldnt be hard to port proper controls for phones.