Shirt Designer / Graphik-Designer

I am Christian, 42 years old, based in Germany and I am searching for a creative Shirt Designer (for "Merch by Amazon" and "Spreadshirt"), who has already experience in this business and a great understanding, what kind of shirts/designs and niche have the potential to sell good on those named platforms. On the US but also on the German platforms.

If you don´t have experience yet in this area, please don´t apply. Thanks upfront!

Best,
Christian