Honestly? I think you are getting hung up on approaching this from the T9 perspective.

Take a look at the mechanical keyboard community. Most people are sane and looking at TKL or even 60% layouts where most buttons people actually use on a keyboard are represented by dedicated keys. But there are some real sickos who go for fully minimalist layouts where they have closer to 20 or even 10 keys. And those are the leyouts where you heavily rely on different layers so that “A” might actually be “Button 1 with modifier X and Y” whereas B is “button 1 with modifier X”. Basically people took the logic of dvorak and went to an insane degree.

And that has the same issues that mapping to a gamepad would. Some people are going to be able to internalize that in a timely fashion. Others are going to spend months using typing tools online to train themselves. And the rest of us are going to say “nope” and move on.

In terms of how to have a better steam deck keyboard? I think there is a lot of room for someone to go full keeb-pill and take advantage of the physical buttons. I would 100% watch that youtube video, maybe throw a tip in a tip jar, and then have a new appreciation for the touchscreen keyboard the next time I have to enter my Warframe password. But I still think that if your game is heavily reliant on having a keyboard… it isn’t a Steam Deck game. And that is fine. I am not going to play DCS on my Steam Deck. One of these days I probably will futz around with streaming X4 though.