Sorry for the bad news, but in principle there is no solvent for both these glues.
In the case of PVA, I would recommend to give the figures a bath in warm water for some time. The PVA glue will absorb some water, I suppose, and become softer, so that you can separate the parts more easily.
For 2K epoxy, there is only the method of using violence, I'm afraid.
It is funny that you have problems with these two materials, because this exactly mirrors the situation in archaeology: But PVA and epoxy resin were used liberally by earlier generations of museum experts for conservation and reconstruction of artefacts. Today, these polymers are seen as a curse, because they are so difficult to remove.