Yup. I know, but that was the only “official” article in reference to Steam Deck.
For the OP, mind you - this is a bit aged. But the majority of similar threads link into this one or other ones that ran adjacent to it. Yes. It is focused more on SteamLink than the Steam Deck, but especially with the third-party/remote screens and such, it is still a good standing resource until the policy has been updated and/or changed.
And some others that are good to read through, should you have the time and inclination:
The best advice that can be given is that if you’ve got to figure out some convoluted way of doing something? Often times the best answer is the safest answer. If you have to ask, the answer is likely “no.”
You’d have to ask yourself how much are you willing to risk an account.
Something your spouse may want to do is reach out to the Accessibility team if they haven’t already. While there is never a guaranteed reply, we have seen several people come back to say that they had received a response from them. They may be able to help with some suggestions or whatnot that would keep your spouse on the legal side of things.
Good luck to you and your spouse!