Maya PLE is fine for learning Maya, but IIRC the renders are watermarked.

DAZ Studio is roughly equivalent to ProPack, but as more plugins get added it may get closer to P6.

Shade7LE can import scenes from Poser, but you won't have displacement or other node based features. For better compatability with P6 you'd need to upgrade to Shade8.

Vue3 doesn't import Poser scenes directly, an exported OBJ file has to be used. To be able to read a PZ3 you'd need Vue4 or Vue5 and and add-on called Mover (which is built into Vue5 Infinite).