Filco Majestouch 2 one of 3 most quality mechanical keyboard have USB to PS2 adapter inside box.
She don't have LED or such things...Maybe she could work.
Compatibility USB and PS/2.
PS/2 Interface is also available to use PS/2 conversion adapter included in package.
Windows XP/Vista/7/8/10 PC with PS/2 port or USB port
I'm not sure now, but they costed more than RGB keyboard, and worth more than RGB keyboards.
Price was almost 200$ in some moment but later drop I think below 150$.
I was interested but extra cost of PBT keycaps increase price more.