Trying to start a USA based printing supply start up for dropshippers I will not promote

I own a clothing brand and primarily use dropshipping. After thinking about it, I’ve decided that I want to become a supplier for other dropshipping businesses like mine. I’ve noticed a lack of U.S.-based suppliers, and I have the funding to purchase a commercial DTG printer, along with the space to operate it. My focus would be on T-shirts, sourcing blanks in bulk from China and offering U.S.-based shipping to ensure fast delivery for customers. However, I’m struggling to find detailed information on this type of business—most of my searches only lead me to dropshipping companies. Does anyone know where I can find more insight into becoming a supplier for dropshipping businesses? Any advice would be greatly appreciated. Thanks! I will not promote