Aha! Thank you both.
Instead of running the n7nix code, I've been using it as inspiration, and gotten things to recognize the sound card, thanks to n7nix, Lars and Karl and all the docs that exist in the wiki.
I ended up doing a(nother!) stock buster install, adding the tlv* modules to my /etc/modules, modifying my boot/config.txt, and now it looks like it's on it's way to functionality.
I may add a page to the wiki with my approach in case someone else wants to do it by hand as well.