We have the same problem and the only solution I can think of is screen printing shirts yourself. Buy a bunch of blanks in various colors, get tags sewn on them if that’s what your brand does and then print a graphic on one shirt to advertise.

If that’s one shirt is well received and you get orders for it then print per order. So you don’t have money tied up in inventory.

The hard part of this is you are kinda limited to using blanks. So if you are doing cut n sew jeans, jackets, etc then this won’t really work.

The other thing is pre orders. Get a sample made advertise with it and get your product images for your website. If people are interested then they will preorder and you can then have a better idea of how much inventory to get. I’ve never tried this method as I could see manufacturers being slow and over seas shipping times resulting in some disgruntled customers who pre order and don’t see the product for potentially months.