I don’t know if there is a universal name for them. I would call them a safety chain attachment or a safety chain hanger. You could make them out of any sturdy piece of flat steel that is thick enough to withstand the load.
They are called safety chain brackets. Companies like Reese, etc… make their versions. Not cheap though.
I would go to Princess Auto and they should have something you could make work. I bought heavy duty eye bolts that were on sale once that I used to hook my safety chains to.