Hello, I was looking through the sky130 pdk and noticed that the nfets don't have any hvt cells, only pfets do. nfets are limited to lvt, nvt and zvt cells. Is there a problem with my installation or is this standard practice?

This is correct. You don't have installation problems. Only pfet hvt devices are available. Probably because they come for free by using the various P and N channel implant masks (or no implants, I don't remember now). A hvt nfet will probably require an additional mask (or more).

Understood, thank you!