There's exporting as obj from Daz to blender and back in Daz and then to VaM:
https://hub.virtamate.com/resources/how-to-use-blender-to-sculpt.2302/
Be sure to both import and export the obj with "Keep Vertex Order" option in blender, there's no fixing it if you forget. (there _may be_, but it's pretty damn convoluted). For simpler morphs it's very straightforward.
As for corrective joint morphs, you can export a posed figure as obj and import that to blender so you can properly see what you're correcting. I'm pretty sure there's options in Morph Loader Pro in Daz for applying an already posed obj to a figure with the same pose. I don't know what they are precisely, but at least I think it's the right direction to look into. This for example
seems relevant, even though it's for clothes.
Zbrush will also probably work and is integrated into daz with some plugins, iirc, but I don't believe there's HD morph support in virtamate, so you'd have to make sure you're morphing at base level. I don't know how to do this at all, but I think it's very possible. However, learning blender is always a plus afaik.