Yeah it's a lot of fun and I already tried it, it works perfectly fine
as long as you set the dpi of an image to at least 300 and use a t-shirt
printing company that has high quality material for shirts.
Since I'm only doing it as a hobby and I don't have a lot of time for
it, I use a free software called Krita with a small Wacom pallet that
you have to attach to your monitor (some really cheap things just to try
it out :p). I don't have any art back...
I've been doing power lifting for a few years now as a hobby, and last
year during covid boredom I started doing digital painting and drawing.
Here is my most recent work, which is still a work in progress:
