What can I spray on my new glass shower doors to shed water?

Use a daily shower spray

Just use your towel then put it in the washing.........

for some reason my brain says rainx yup....shower door water repellent Is availabel.

You could look at the automotive section of your hardware store...is there a windshield product that “sheets” the water?

Liquid Glass - this can be purchased at any place that sells car was (It is higher end $25-$30.00), but you can also shine your car up after doing your shower door😉. My Grandfather who use to build race cars & show cars told me this secret after I asked him how his 25 yr old Buick had NO rust & the secret was polishing/waxing with Liquid Glass. It does work great on both.

RainX is the best thing to use. You will have to reapply is at some point like you would on your car front window, but it works like a champ. something else I discovered if you have tile walls in your shower. Use car wax, that will bead the water and dry clear, particularly if you have hard water. It helps tremendously with preventing scum build up too.