I took a flyer on these when I was planning a summer trip to Spain. At home, they were comfy, lightweight and appeared to pack down super small.
But on the road, in the hot southern Spain sun, they became something magical. Despite my best efforts, they refused to stink; even after multiple days. They don't wrinkle, they do pack down super thin, they're comfortable.
No affiliation - this is where I got mine and they ROCKED: https://onno.com/store/bamboo-t-shirt-men/. Both the original and the ONNO cel are great, it's just a matter of how you like your shirts to hang on you. I bought one of each.
Couple that with bamboo underwear from amazon and you'll be a happy camper.