Consider contracting a fulfillment service to sell merchandizing
See https://lists.autistici.org/message/20201025.192502.b9550ab7.en.html
and for the latest discussion on that topic see: https://lists.autistici.org/message/20210119.192920.4864dfcb.en.html
For example:
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information