Researched this for a bit: there is some hardware for PCI supporting it, but Windows 10/11 not, and Linux is still work in progress, so no real support on OS level, only for some iOS/Android devices.

That's not quite accurate, I don't think.

I've definitely used STA and AP modes concurrently on my Windows laptop with the operating system's built-in internet connection sharing function to help troubleshoot a problem in the field.

That was around a decade ago. It didn't take any extra effort on my part; I just told it to do the thing, and then it did that thing.

it might be interesting to use unused or extra wifi cards to support this. My pc motherboard has both wifi and ethernet and I only use the ethernet. That card does absolutely nothing at all.