Sturmey Archer 3 speeds have alternate axles to build up a narrow axle hub .

Brompton uses a 120 wide Hub in their folders..

People have used The Sturmey 8 speed in Bromptons,
taking off and thinning axle spacers , to reduce width

Los of newer hubs are 135 width. Alfine 11 one of those. [afaik]

I have a mountain climbing capability with an AW3 + a Schlumpf Mountain Drive,

a 2 speed planetary Crankset , Made in Switzerland.
so low range, offers the 3 hub gears another run thru.
Shift is internal, no change in the chain tension so no chain tensioner needed .

Herr Schlumpf also makes 2 overdrive cranks to use a small primary chainring set
the planetary multiplies the external cog ratio [1.65X or 2,5X]