Agreed with Kontact
if you don’t want to get a spendy hub & wheel…
https://www.paulcomp.com/shop/compon...ear-hubs/word/

… using any 135mm cassette hub and just use one cog. Or add spacers and have a single cog.

Surly might be less spendy….
https://surlybikes.com/parts/ultra_new_hubs
of course finding an off the shelf option could prove challenging.