Experimental Nasal sprays are being developed that appear to reduce nasal viral load considerably

From a preprint:

This one has not been tested in humans but looks great in the lab.  Might be used for prophylaxis when entering enclosed spaces.  It is an OTC sinus nasal spray whose active ingredients are xylitol and grapefruit seed extract.

Xylitol has a long history of being safe and beneficial in preventing bacterial pathogen infections.14 It is considered a prebiotic due to its positive effect on the microbiome, reducing pathogenic proliferation.15 The use of xylitol in oral health to prevent dental caries and periodontal disease has been well documented as safe and effective...  Because there are no risk factors in using the X/GSE combination therapy, and the nasal spray is over the counter available without prescription, and the spray allows for comfortable long term mask wearing, adoption of this preventive anti-viral therapy should be encouraged.

 Here's one other nasal spray, nitric oxide, that has been tested on humans, but the press release never says whether it improved their clinical course.  It did reduce viral load.  Since the product is applying for an EUA, it does not need to show clinical benefit, only that its net effect is presumed to be better than nothing.