However, the configuration utility for it is part of steam, it is a highly configurable controller, so much so that it could be argued much of it's utility is lost without this configurator.
While we could argue about the state of Windows, Steam also did not have to engineer it this way and the requirement of launching through Steam feels deliberate.
From what I can find, as others have mentioned, the 8BitDo controllers don't require Steam to be running to work. I presume the PS5 controller likely also does not (I will test this later)
My PC may have installed something on its own, but I did not.
However I don't have an issue if there is a driver, the requirement of Steam running and apparently launching the game through steam is the issue here.
Edit:
I just realized I completely missed the not in your message:
> I can confirm that you do not need a Sony/8BitDo user account or any of their software running in the background for the controller to work.
so I guess my reply was not necessary, I need more coffee...
Valve does deserve criticism for the royal pain certain things are though. For example non-technical users will absolutely struggle to get Proton working without Steam, the process in doing so is purposefully kept undocumented and esoteric. There's 100% a little bit of undesirable obfuscation Valve does to push you towards just using Steam to run their OSS. It's definitely non-Free in the purist sense.