I swapped to yay after yaourt was gone. Yay is written in Go, so I thought it’s pretty good for me already.
Judging by the code size via tokei, yay is ~8.3k LOC in Go. So I’m gonna guess wildly and say 6 months if designing from scratch and 1.5 months if porting from yay’s source code directly, for a MVP, excluding testing.
EDIT: Wild guess was quite literal, cause I have no experience in porting Go code of this size/nature to anything. But a few months seems doable from my limited experience in user facing cli tools, when design choices are made and battle tested already (inb4 this becomes my famous last words). In any case most people here know much better than I would.