Looking at the options on their website, I think he is probably an "Americana" (which they say is also called Easter Egger.) They are certainly not Ameraucanas, the breed recognized by the American Poultry Association.
https://www.mthealthy.com/birds/americana
Given his comb, I do not think he's an Olive Egger (when they cross pea combs to single combs, that usually produces birds with larger combs and wattles than what he has). He could possibly be an Olive Egger, I just don't think it likely.
I'm not seeing any other kinds with pea combs that he could possibly be. And since pea comb is a dominant gene, it's not going to just pop up from a pair of single comb parents.
