Why are you pushing OSS?
I could have sworn ALSA didn't work for me in the past, but I'm on a fresh TinyCore 4.7.7 at the moment and just tested it again and to my surprise, I had sound. I have to test that later on the newer version, too. If that's the case, my main issue will be the lack of Opus support. Sorry for the noise then.
I wonder though why it is not possible to select the OSS module in the 5.x VLC extension. The nice thing about OSS is, that it is smaller. The version in the repo (build 2005) hasn't been updated in a while though. The current version (build 2009) has some fixes, according to its release notes. But if nobody here uses OSS, I guess there's no point in updating it.
I'll check later, if ALSA works for me in TinyCore 5.x, too, since I'm still puzzled why it just worked here at all. I might have accidentally used another computer in the past, where it didn't work.