The niche bullshit will continue until… Well, actually it’ll continue indefinitely.
https://www.printables.com/model/791788-pilot-parallel-cap-with-pocket-clip
I just got done solving my years-long festering irritation with my spread of Pilot Parallel fountain pens, which come with a caps that ain’t got pocket clips. Among other flaws. They bloody well have clips on 'em now.
You could make a second part that’s always screwed into the screwy bit and then remix the new cap to pop into that!