Learning with Pibby: Audition Read Clips
These leaks were confirmed by a demo reel posted to Soundcloud in 2020 that resurfaced once the world discovered what Pibby actually was. It shows what Bun Bun and Alloy Boy's lines in the casting call were (which, in turn, give us more insight to what happens) Pibby and Melira's lines haven't been found (yet).
Property Dan Greenley, Adult Swim, and Warner Discovery