I never learned to ride a bike. It is my deepest shame.
You can use a 3/32 shimano cassette cog and file off all but three equally spaced inner splines... and round those ones off to fit in the cog carrier of the hub.
The Sram one linked should also work.
You also have to be wary of chainline - if you get an offset cog like the SRAM one and you used to have a flat cog, you will likely have problems. Same goes if you now have an offset cog and switch to a flat one.
I initially wanted to go 48x24 so I could keep the original chainring, but I could also go 44x22 by replacing everything (chainring, sprocket, chain). It's just a shame to replace all that when it's otherwise perfectly good.