I just want to offer my thanks to everyone who replied. I wasn’t even aware of several of the products mentioned.
While I haven’t taken pictures yet (lol), I did pick up some of Windsor and Newton spray mentioned above (it was locally available and much cheaper than most of the other suggestions), and it has worked beautifully, drying very flat and causing no detectable color shift. Assuming that it holds up to handling, it will be my new go-to. Otherwise, I will try some of the other suggestions. Again, many thanks for the input.