If I may make a suggestion: there's a hugely underserved population of short (< 5'6") men who cannot buy good quality, well-fitting clothing in the US. I would love to see a small shirt manufacturer tackle this demographic.
Our XS fits 5'6" well, but we haven't tested to see where it starts to become too long. Here are a few people that are 5'6" wearing it:
https://pistollake.com/images/examplefits/Erik_XS.jpg https://pistollake.com/images/examplefits/Zach_XS.jpg
NAME SIZE HEIGHT WEIGHT PANT SIZE CHEST STOMACH BICEP ARM LENGTH Zach XS 5'6" 140 28/28 35" 31" 11" 28" Erik XS 5'6" 130 28/28 35" 31" 10.25" 28"