My Windsor Nano is pretty stout, would not hesitate to recommend it even to a heavier rider.

On something designed for single speed like NormanF's BigShot or the Sillgey Picolo, you could certainly run IGH w/ coaster brake; on my geared Nano w/ vertical dropouts, you could only run that setup if you found some "magic ratio" that would allow for proper chain tension without the use of an adjuster or tensioner. You could certainly run an non-coaster brake IGH hub with rim brakes and a tensioner.

The Nano has eyelets for rack/fenders. Looks like the BigShot does, too.

451 tires which come stock on most mini-velos are going to be a special order at most shops which do not carry recumbent or folding bikes. But they are readily available from distributors. Tire size/style is limited to 1-1/8" or 1-3/8" sizes at QBP. Swapping to 406 wheels will give plenty of tire options.