Well… they do offer a usbC to jack in their online store (but you can buy from whoever you want).
But I guess usbC to usbC would work which would make sense if you’re using your charging cable which is (more or less likely to be) an usbc to usbc cable.
I might be wrong tho, but we have usbC earbuds and headphones (or was it apple’s lightning wired earbuds? I’m not sure)
But nontheless I think minijack would make for a more versitile device and I was a little dissapointed when I learned that Fairphone 4 does not have jack. Well FP5 does not have it either but I don’t care, I can get jack to C adapter cable from my friend if I ever need it