Adapter to interface camping propane tank like big grilling one
Shopping questions are off-topic here.
However, I was able to find what you're looking for by searching for &quot;coleman&quot; (since they're one of the most popular makers of 1lb propane tanks and the camping grills that use them) and &quot;1lb propane grill adapter&quot;.
I was able to find this at Amazon in pretty short order.

Various other adapters likely exist, but I would caution you against trying to make your own with two ends and some tubing. Liquid propane can be 100-200 psi and it's difficult to handle that with DIY tubing.