Maybe you don’t need any conditioner!
As far as a glove opening and closing, the thing that gives the most resistance is the heel padding. If you can loosen up that pad it goes a long way toward letting the glove open or close.
Try this...hold the glove by grabbing each side of the heel padding. Work it back and forth as hard and as fast as you can. Keep working it and you’ll feel the padding start to get loose.
You can also find all the hinge points, the places where the glove naturally wants to fold through the palm as you open and close it, then bend and work those points back and forth.
I’ve gotten gloves game ready doing nothing but this, then playing catch.