Supaplex did supplement their map with open data from the municipality though for the street outlines as far as I understand (I've asked), so it's not 100% OpenStreetMap data used there.

Totally awesome and inspiring nonetheless though.

Right, from https://supaplexosm.github.io/strassenraumkarte-neukoelln/po... (translation https://translate.google.com/translate?sl=auto&tl=en&u=https...), there was an extra curb data-set used. I've actually found a few of these (https://a-b-street.github.io/docs/tech/map/geometry/index.ht...), so the approach is maybe repeatable.

Regardless, the design choices and color scheme are something I would love to adapt.

You can definitely map curbs in OSM if you have high resolution imagery: https://wiki.openstreetmap.org/wiki/Key:area:highway

Do not expect however mainstream data consumers to support it ;)

That is gorgeous! I want it.