That is awesome that they actually use Linux for the design work! I did eventually run across the Fedora Magazine Article talking about that. Definitely a great operation! I wonder how well the embroidery works on a t-shirt? That is certainly unique.
The various products up on redbubble, are those usages OK? I haven’t actually looked at whether the quality is decent or anything of that sort, but if the usage is a bit on the shady side I will steer clear.