Following a request on reddit, I had the game preloaded just to look into its ultrawide support after the developers famously claimed that it would be impossible in this game.
I started working on a solution as soon as the game was released and shared some of the screenshots on the WSGF Discord.
Some time later, a manual solution based on the common aspect ratio bytes was posted to the WSGF subreddit.
I had a bit of sleep and then continued working on my own solution, primarily focusing on the split screen field of view. The FOV was a separate value detached from the main FOV, so it took some experimenting and time to find that, as well as a way to make the split screen scenes fill the screen and possibly improve the interaction icon placement (severely offset otherwise).
Hours of non-stop work later, I had all my scripts and calculations in place and the trainers compiled. Before I got to publishing, OnkelJupp also shared the common 39 8E E3 3F bytes allowing to improve the interaction icons' positions at 21:9 and make the split screen scenes fill the screen. I didn't know about it until later and it could have stopped me from publishing what I had if I did.
Nevertheless, even past all of the posted community findings, my trainer had the unique benefits of supporting Microsoft Store / Game Pass versions of the game, and featuring fully automated and perfect real-time vertical FOV adjustment for all scenes (contrasting to the one FOV value, and vert- split screen outcome of the manual fixes).
The feedback has been surprisingly great so far, though I expected at least some bug reports from 21:9 users to have something to act on. The fix is reportedly good for 24:10 as well but, unfortunately, I could not produce a fix for the interaction icons for 32:9 and wider. Nothing is impossible in software hacking and it's a matter of time and dedication, so I may still give it another go later, as it was with The Outer Worlds viewmodel.
Update: There is now 32:9 and 48:9 support, among other resolutions.