Now I'm thinking that I'm gonna make these kinds of merchandise and sell these platforms. But don't know about the market potential. Is the people of crypto ecosystem are really interest to buy crypto merchandise stuff?
You don't need to prepare stock of goods in advance as a business start if you don't know the potential. I think you can use the pre order method by only preparing previews of the t-shirt or at least you have mastered graphic design to accept custom design orders.
And obviously you have to have a t-shirt manufacturer standing by to meet demand on time.