It looks like Blender 2.92 and higher has an Emission Strength input on PrincipledBSDF where you could plug in that LightFalloff node pretty easily. Not sure how Cycles upgrades are going to work in Poser. But see https://blender.stackexchange.com/questions/164075/how-do-i-change-strength-of-emission-at-principled-bsdf

That page also suggests that for us the solution would be Cycles --> AddClosure --> PrincipledBSDF with the other AddClosure --> an Emission node, so you can plug the LightFalloff node into the Emission Strength input on the Emission node.

It's not as clean as Cycles --> PrincipledBSDF but it's really not that bad.