How often after cleaning does the dust cause a problem? If it's not terribly often, mount some steel automotive brake line out of the line of sight of the camera lens but pointing at it. Then run the line to, say, a blowgun that takes the same size steel tubing for the blow line. I've made a number of blowgun extensions for cleaning hard-to-reach areas or for use cleaning floors without bending over. With the line mounted solidly, you should be able to mount the blowgun somewhere convenient but out of the way and just tap the handle once a day. If you'd prefer it automated, there are pneumatic solenoid valves that could be rigged up with one of the many smart home automation systems or even manually but remotely through some cameras themselves like activating the heater, wiper, fan, or whatever.
If you prefer a glass shield of some kind, try wiping it with dry newspapers.