I like the idea of a single legged (composite?) fork on the road, especially for something like my commuter where it does away with taking a wheel out for changing / fixing a tube…
I would be wanting a front disc or drum brake though, for one thing having a caliper straddling the tyre / rim sort of affects the flat fixing access benefits a bit, plus if you’re going all fancy and new-fangled you might as well go the whole hog.
Although in terms of braking forces a single leged, disc brake fork is going to have to contend with more stressing of that single leg / crown than a rim braked one so there is a major benefit to doing your suggested way…
Using a 20mm standard hub makes sense to me, designing a fork/hub with the bearings in the leg itself would be a fun exercise but I’m not sure it would actually be beneficial, probably adding cost and even mass, more for novelty than function…
It can be done in a Garage, with some help / input form others I reckon, first thing to figure out though before the actual detail of it’s construction is the geometry you want, A-C dimension, offset and steerer dia…
I like it… Do it!