This is a super basic Python script I quickly bodged together for ripping .vag files (which can be read by vgmstream) from The Simpsons Skateboarding's ASSETS.BLT file. Decided to share this on the off-chance anyone finds it useful, though note it is very much not robust or polished or anything.
python rip.py "path/to/ASSETS.BLT"
The music track 'Springfield Mall 3' does not get ripped by this script, and I have no idea why. I'm guessing there's probably some cursed reason like it being stored in a different format from all the other songs, or being compressed, or something like that. But whatever the reason, it can be ripped from the ASSETS.BLT file in the E3 Demo, which is officially Good Enough™.