Not entirely sure a clean method in plugin will be possible in 4.21 at all, they stated that they were adding to it post 4.21 and their repository version is on 4.22 already. I would have to find a spot to edit the action manifest that they are generating without screwing over the input stack, the file is generated on every program launch…
I haven’t tested yet if re-setting the action manifest clears handles, it likely does which would put a large damper in doing it through plugin for now. Directly in engine source it would be very easy though.
As for finger values, previous knuckles used the finger curl values that are already in the legacy inputs, I have heard a few people saying that those no longer function, I wouldn’t know since I have been developing directly with the skeletal data instead and have never needed them. There are also seperate per finger curl values that you can bind to in openInput and a grip value.