There are master works on the class 2 list for horn (the middle movements of Mozart 2 and 3, for example).
Our rule is that the kid must make a division 1 rating on a class 2 before they can attempt a class 1 solo. The only exception is if the kid is in private lessons and their teacher signs off on the class 1 solo.
Another poster mentioned Mozart 1. I agree that (especially the first movement) is one of the most do-able class 1s. Especially, if the kid can be taught all of the Bb horn alternate fingerings for concert middle-C and below. On last year's PML the original key (D) version was taken off of the list and only a transposed version (Eb) was there, which as a horn player bugged me. This year, they've added the original key version back as a class 1, but the requirements are "play at least movements 1 or 3." This is problematic, as Mozart 1 only has 2 movements. Just add this to the list of vexing things in 2020 (the PML part, the 2 movements have been vexing musicologists for much longer). I'm sure the PML will get fixed for next year (maybe sooner if someone important reads this post). That said, I usually start our ambitious young players off on Mvt 1 of Mozart 1 (in D).
I also agree with the poster who mentioned, the Franz Strauss Nocture (Opus 7). It is a gorgeous, lyrical class 1 that is not too hard technically, but does require 3 octaves of range. I generally recommend this to our kids who need to work on their sound across the range of the instrument.
FWIW, both of these are on IMSLP if you'd like to take a look.