I don’t think they’re handling their current scale well just in Europe, even. VoLTE works on a limited number of carriers even in Europe. e.g. only T-Mobile is recommended by FP in Poland, but it’s just one of the four large telcos. I wouldn’t expand if I was at that point. Plus, they’re busy with making their support less horrible (see post on their forum) for now.
edit: damn fp6 doesn’t support any Polish carrier, a step down from FP5 https://support.fairphone.com/hc/en-us/articles/9779766652689-How-to-set-up-4G-and-Wi-Fi-Calling
Back when phones had character