FPGA based devices that can do this, and quite well, do exist, they're just expensive. The RetroTINK-4k Pro is the top of the line as of this writing but it's a $750 converter.
For emissions related components, EPA rules do kick in though. While the current administration appears to have paused enforcement, their position for many years has been that running anything except factory approved firmware on an ECU or other emissions related computer constitutes a “defeat device” and is illegal for an on road vehicle subject to emissions controls. (Granted, in practice 99% of the reason anyone installs new firmware on their ECU, or switches to an aftermarket ECU, is for a “tune” that does affect emissions. I’m sure there is some edge case exception, but it’s very rare in on road engines.)
The alternative, and there are a very few tunes that have done this, is to prove to regulators that the tune does not negatively affect emissions in any way. In practice this is done by getting a CARB exception since they’re the ones actually checking for tunes.
But I'm not even sure because GH auth system is all over the place and downright nuts in some places...
e.g a fine grained token with repo access can't curl a tarball with the usual URL, it has to use the /api which makes tooling that constructs URLs from repo names and versions break with no recourse as soon as you disable classic PATs
The biggest problem with SE for me, and this is related to the culture issues you're talking about, is that the site has no good way of deprecating "formerly correct" answers. Even if a better, more correct answer is posted later, the reputation system has a huge incumbency bias in favor of older answers that have accumulated upvotes by being the best available answer at the time.
Their knowledge repository is slowly rotting under the weight of having to ask every time "okay, is this correct-sounding, highly upvoted answer actually (still) correct, or is it 10 years out of date?"
