shop=car_parts with some tag for “hahaha, not really for your car”?
shop=truck_parts ?
something else?
Yes (10 in use already)
No, because taginfo suggests the subtag there is “what sort of part”.
I think that that would overcomplicate things, but there are a bunch of other values to look at - where car_parts is part of a tag with a colon in it, for example, and also wholesale. Also the “catch all tag” agrarian** includes some “parts” options that may overlap.
** there are some proper “comedy taggings” of shops with that tag. This one looks like a restaurant (“The Poultry Farm”) that specialises in Chicken etc.
I created Tag:shop=truck_parts - OpenStreetMap Wiki (and not added it to say Key:shop overview page as usage is tiny, at least for now)