SIGH.....
Ignore the 8bitdo Ultimate controller I think for Steamdeck entirely. Both models.
Can confirm on the 2.4ghz model(cheaper non-BT) that x-input DOES NOT work and may never be updating to do so(8bitdo recently made a statement that it is
only meant for Windows use).
Then there is this video...which led me to buying this cheaper $49.99 model which seems to work over d-input:
View: https://www.youtube.com/watch?v=Ug2J2DHLk3g
Well...seems not enough testing was done by RGK. Problem myself and many are discovering is that even though d-input works and connects, the home button has a bug of glitch where it will initially act as a "Steam" button, but very quickly revert to being mapped as start(at least for me). Meaning there is zero way to get Steam button functionality. Dealbreaker right there.
Other issue is that while the d-pad, left stick, bumpers, and face buttons work regardless in various testing...the right stick and triggers are completely non-functional.
RGK may not have tested those if using only on emulation, but load up any first-person game and its unplayable.
Apparently some reddit users have hacked together a fix that forces it to be recognized as an Xbox controller by doing a lot of edits on the backend, but meh...I need a turnkey solution here. This controller was close, but for now its a hard pass for anyone interested for Steamdeck use.*
*Note the pricier BT version does seem to work -only- via BT mode, but with caveats of its own. Check big reddit threads about that version for guidance.
Shame as I love the feel and the docking station. It was almost perfect, but perhaps 8bitdo will develop a version designed around the Steamdeck in the future. This ain't it though...