I have a steel sheet metal cabinet that uses the pictured brackets to hold up shelves. It has a runner in each corner on the inside, with slots which the brackets fit into with a little tooth on the back, which is 3/8" wide (shown below). The shelf sits on top of them. Similar to a push in shelf bracket. I would like to install some more shelves, but do not know what the brackets are called, preventing me from getting some more. Can these be identified to assist in purchasing some?
Using the term "shelf clips" I was able to locate only one resource, a company called Locksco which has a clip that appears to be similar to yours.
During the search, I saw also the term "metal cabinet shelf clips" but using that search term did not present the previous location/link. At US$20 for quantity four, they certainly are expensive.
Note also that no references of scale are apparent. They could be too small or too large for your purpose.
Additional searches proved fruitless.