Sure, they both work fine with a true AT keyboard.
I'm using an old PS/2 generic keyboard, and tried another HP PS/2 keyboard I had lying around, no difference.
The PS/2 keyboards behind the adapters receive some power as the num lock etc.. light on and off on key press. But the BIOS gets stuck at "keyboard error" and pressing F1 to continue doesn't do anything, nor Del to go into bios.
Motherboards are PCPartner OPTI 486 VI & QDI V4P895P3/SMT...both react the same. No barrel battery, no damage.
I'm using adapters like this off eBay: https://www.ebay.com/itm/265155844755
I have several of them. Same adapters and keyboards work fine on a later Zida Tomato BX98 board. That's why I wondered if there was something different with these old 486 boards... this is weird 🙁
The HP keyboard I'm talking about is one of those infamous standard keyboards that were probably in half of all companies in early 2000 😀 I'd expect them to be super standard and compatible?