As said heat, and cold spray with carb cleaner or caned air, to shock the bond. Find a screwdriver that fits the slot well and tap with a hammer to break the bond. The lacquer does not help.

Try to break the wear strip loose from the screw head and the wood,(tap it with a brass drift) then you only need to deal with the thread bond.

Nice find, that strop is most likely a KANOYAMA/ KANAYAMA CORDOVAN. Does it have the Cream or Brown linen?

Love those old Kanoyamas, especially the linen. Hydrate it slowly, looks like it needs a bit of oil.

Love the razors also, glad they landed in good hands, enjoy.