I think the original info regarding Federal only having a "reduced" load for 20 gauge was an error.
Believe the new TSS 20 gauge will be available in 1 1/2 oz full velocity (as well as a reduced load).
Keeping in mind the TSS is 20% "heavier" or denser than the Federal Heavyweight pellets . . . . . .
It's likely a #9 "reduced" TSS load might still have a comparable effective range as the original full-power #7 Heavyweights, simply because the #9 TSS will have more pellets per ounce, and with a #9 TSS pellet having comparable penetration to a #7 HW.
Since on the subject of juvenile hunters, or any of us for that matter,
we can use #9 TSS in a more open choke, which can provide larger diameter patterns (less chance of a miss),
and maybe still have the same or greater effective range of traditional lead #5 turkey loads with much tighter chokes.
A typical old 20 ga single shot with a fixed modified choke will possibly be deadly at 40 yards with #9 TSS.
Just have to pattern it to see.