As far as preparing... Maybe read half of a Grade 1 in 4/4 time in the right key signature. I don't want to violate Steve's wishes here on information here beyond that. I didn't see a group play it and not get a 1 as I was judging. Willie Owens easier pieces might be good to read to prepare.
On a side note I wish UIL would continue to have the Grade .5 available for Non-Varsity 1C groups and Non-Varsity 2C groups. My Non-Varsity junior high group I run was never able to get the momentum back up after two weeks of shutdown for the winter storm and COVID in February for me to take them to contest, but it would have been great for them on a normal year though!