For those bikes hubshell is 28 hole, axle is narrow, 112 I think
could core swap with a 36 hole shell,
but the short cassette is for 2 cogs , BMX cog shimano pattern
no big cogs . Hyperglide cogs are not so hot on single speeds

Mk 3 Brompton got a SRAM also for 13,15 half step,
but used Sturmey pattern for the cogs,
so you can put a sturmy cog, 1/8" thick up to 22 t.

may be a part kind of like the 9x3 hub , but shorter..
dual drive hub may have some interchangeable parts