I can't immediately name any motherboards that have USB 3.1 Gen 2 type A headers for the front panel.
Lots of motherboards have 3.1 Gen 2 type A headers at the rear - is that what people were talking about?
Nope. My Asus Prime X470-Pro actually says it has that header for front panel. Which makes it very confusing compared to the Asus Prime X570-Pro manual.
This is Asus has to say about the X470:
First spoiler = specs, 2nd spoiler is several pictures from the manual.
This is about the X570:
First spoiler = specs, 2nd spoiler is several pictures from the manual.
What am I trying to say?
I'm trying to say here that the webpage for the Asus X470 Pro says it's a Front USB 3.2 connector, while the X570 webpage says it's a front USB-C. They look the same and are at exactly the same spot. I checked the manual for it, I even compared the individual connectors and they're all the same (see last picture in both spoilers), making me think that the advertised "Front USB 3.1 gen 2" connector is the same as the USB-C header from the X570. I found it very confusing.
So there are motherboards who say they have a front USB 3.1 header. But I don't think they're regular USB 3 headers (they're usually at the bottom of the motherboard).