The converter converts from Famitracker and supports instruments with Pitch/Volume/Arpeggio/Duty. Nothing else is supported; no effects nor volume columns. DMC is not supported,
It uses 12 bytes of zeropage and $100-$156 in stack space. The converted songs are not as space efficient as other engines, but they're small enough for my purposes.
Anyway, you can find the code here: https://github.com/pubby/penguin Keep in mind this is not a library; I wrote the code for myself.
I'll attach a ROM that plays Ralph 4's music.