I don't know of such a public listing, but you can find out the numbers of the U-23/U-18 players who have appeared so far in the Checkatrade Trophy matches this season by looking at the club website:-
Under Matches, click on Checkatrade Trophy. Click on the Results tab, and then click on the...
Given a squad numbering system, it's going to happen though, isn't it? We currently have 63 professionals on the books, and given that 6 scholars have also been involved in the Checkatrade Trophy matches (where squad numbers are also used), you are going to get shirt numbers up in the 60s, 70s...