I have learned that clementines, pomelos, and kumquats produce zygotic seedlings, and can be used as the female parent in a cross. I have not found a lot of info on pollen fertility in citrus.
The vast majority of citrus can be used to pollinate other varieties.
Kishu is one of the ones that is a very poor pollinator, but still not impossible.
Very few citrus cultivars are completely pollen sterile.
It is possible to use other citrus varieties as the female parent, but the great majority (70-98%) of the seeds will be nucellar clones of the parent, so that could make things difficult.
Oranges tend to be the very worst, almost completely entirely nucellar.