The state of retargeting 2.81?

Greetings ,I animate Characters externally
(Iclone pro +Daz Figures),and FBX Export from Daz to Blender 2.81 for EEVEE rendering.

My results have been fantastic even with facial & lipsynch.

Is there anyway to globally replace the animation on my existing FBX imported figure in blender, with new external Motion Data
from the same identical source rig(ie retarget)???

FYI I have seen the Diffeo and G8 to blender plugins however
I refuse to have fleeting, third party plugins be the single point of failure in my pipeline .