I’ve never seen stretchy wool. Wool fibers themselves are not stretchy at all.
This is a good list of specialized wool bedding companies:
https://forum.mattressunderground.com/t/wool-mattress-pads-and-toppers
I know at least one wool specialty bedding supplier offers raw wool batting. Unroll a layer above your latex maybe inside your mattress case? (In looking at it myself, it’s actually dimensioned very well for using in a mattress and an excellent price -$100 for raw extra thick eco-wool would cover a king, with no seams requires). Example here: