Admittedly Cycle use is a specialized application , so this is slight drift to general wear.
I prefer to carry on belt , and use the clothing to conceal rather than hold the gun per se . For several years Wally World sold the Dickies brand Camp Shirts , and these were ideal. Loose cut , square tails , and fabric with a little more body to it than the actual Hawaii style shirts. Variety of patterns suitable for casual to semi-respectable wear. Sadly discontinued , I still look for them at thrift stores. Several of the on purpose "ccw shirts" should be as good , but at several times the price.
The Dickies work shirts are also loose , and have extra long tails. Conceal great , but not as suitable for dressier occasions.
Vests ( and fanny packs for that matter ) depend on the setting and your mode of dress otherwise. I frequently wear vests in regular life, so it blends in on me. I have seen people in nice office attire with tactical vests which looked to ne like a neon billboard. Fanny packs ( disregarding discussions of speed ) would blend in if you looked like you were either fishing , on a 10mi hike , or obvious tourist.