Here's a new shot, with a white sheet of paper next to the keyboard. Keycaps are filthy, I need to clean that board.
I'd say that in real it looks more white than on these pictures I took. Nearly as white as the sheet of paper actually (while on the picture it doesn't look that white). I have another white ALPS board somewhere in a garage and I could use that for comparison, but can't go pick it due to the lockdown : (

EDIT: and I may as well ask this here... I've got one broken keycap on this board (the stem of the keycap is completely broken). It's the 'Y' key. What'd be my best bet to find a compatible one, with the correct profile etc.? I don't mind if it's not the 'Y' key nor if it's not a perfect match, but something "close enough" (atm I took the '-' keycap from the numpad and put it instead of the 'Y'). No hurries at all and no big deal.