Instead of just fitting music to one ocarina type, you can work out how to fit a whole category of music to a minimal set of ocarinas.
I usually take a small set of Pure ocarinas to Scottish tune sessions - 10-holes in D and G, V-system double in G, P-system double in D. And don't often need any others to fit in.
This is an example, with tunes compiled for a workshop in the west of Scotland. I had no input in this, I'm just giving it as I found it. And it all fits my usual set of ocarinas.
https://www.nigelgatherer.com/teaching/ws/mm/mm-33.html
You will never need subholes or an ocarina in C to play Scottish traditional music. This is a consistent pattern - that selection of ocarinas works reliably for Scottish trad and it's very little effort to pick the right one out for a specific tune. (My 10-holes are in two different octaves for greater variety, but they play the same).
My G double has a European-style first chamber ranging up to B - with that, you don't need a G 10-hole as well, since these tunes never need the high C.
The keys and ranges for this selection are standard for Scottish trad - Nigel's workshops usually have fiddles, mandolins, flutes, whistles, smallpipes, accordions and bouzoukis, and these versions suit all of them. Ocarinas in G and D fit in without adapting the music at all.
https://www.dropbox.com/scl/fi/wf0x069rvoy706bvesuoo/MM-SB.pdf