Even after Izuku becomes a pro hero he will definitely still have TONS of merch.

He probably goes to get new hero merch at least one week and is always one of the first to get limited addition items.

He even made custom merch that matches his classmates and 1-B's costumes while in high school so he has one-of-a-kind stuff.

Everyone was shocked the first time he came into the common room wearing a (Ground Zero/IcyHot/Creati/any other 1-A, 1-B, or Shinsou) hoodie

If GZ: Katsuki isn't all that surprised considering Izuku used to make merch when they were kids. Especially of heroes that work abroad that he was fans of, but couldn't get merch for.

If IcyHot: Shoto nearly dropped his Sobba in surprise because he strictly told his father and any companies he contacted about merch NOT to make them so he's a little mad at first, but it gets cleared up.

If Creati: Momo LOVES the hoodie and asks where he got it. After he tells her he made it they start sharing sewing tips and Izuku promises to make her some merch too.

If Mind Brand (Shinsou): He almost starts crying because he is going into underground heroics and they don't get much recognition. Izuku is gonna be his #1 fan.

[I have more, but if I keep going I'm gonna run out of space :( ]