I have been messing around with creating ANIMs from modern gifs, and I have a workflow setup for that. I have been thinking about having sound for it would be cool, but I don't have any knowledge about it, sorry.
Im sure you know about
https://www.sundin.nu/amiga/ BuildAnim doesn't support sound but source is available so maybe someone dedicated enough could add support for it if any specs for these kinds of files still exists.