The open input plugin still exists, the input side of it was just removed since the valve implementation is native to the engine now as of 4.24, so it just handles the skeletal part.
As for quest hand tracking, Oculus is generally good at providing their own examples (they have a hand tracking one in their branch) so I generally don’t do as much for their API. I had also held off as I saw a pathway for skeletal tracking being implemented into the engine and figured it would be natively handled eventually, sadly I haven’t seen much progress on that recently (likely due to focus switching to OpenXR which doesn’t have a skeletal extension yet AFAIK).
I’ll note that you can still also just use per finger blends with the curl values from OpenInput on a full body mesh as well.