IMO a PITA to keep clean so maybe that is why . You could probably find a cabinet maker who could make that for you . I think trying to put a cabinet under a counter is always is a bit awkward so maybe post pics of your situation.

Contact your local cabinetmaker.

It isn't a homemade door -- it's part of a cabinet we purchased from Expo, which was an "upscale" offshoot of Home Depot that operated in our area for a few years before closing. Because it's in a bathroom, it's not hard to keep clean, but I wouldn't want it in my kitchen LOL! I think the doors might even be some kind of MDF or laminate or something. It just doesn't seem like painted wood to me.

Ikea has a similar door in their kitchen line but really there is no reason two bathrooms have to match. You’ve said you want wall hung vanities, I would let that drive your search. If there is an ikea near you their godmorgan line is great.

Just checked the Ikea website. You must mean the one called Hittarp. https://www.ikea.com/us/en/p/hittarp-door-off-white-70266384/