I've been commissioned by a large company client to add Cyrillic to one of my more successful preexisting typefaces.
After completing that work, since they don't own exclusivity to this customization, I'll add it as an update to that family wherever my fonts are already being sold.
However, I think it could also be an opportunity to expand to other sites. I do vaguely remember I was once considering a site that was focused on selling Cyrillic or multilingual type but for the life of me can't find it now.
Do you have any recommendations for a reputable (and hopefully profitable) partner that would match this description?
Also, FutureFonts prefer typefaces with non-Latin writing systems included.
However, while I like FutureFonts, it seems its concept (offering fonts that are still in progress) isn't a correct fit, as in this case the typeface already has 1300+ characters per style (all Latin based languages have guaranteed support, and now extended Cyrillic is in there too) so at this point I don't have plans for additional expansion.
There is one more place Local Fonts run by Stefan Peev: https://localfonts.eu/
PS - Even if Vika doesn't have time to do the primary work I'd recommend hiring her to review the end product as a second set of eyes and give feedback. I always hire someone for that role in language expansion because there are things only fresh eyes can catch.
His fonts: https://fonts.google.com/?query=Cyreal&subset=cyrillic¬o.script=Cyrl