I'd love to play it as webbrowser-game, while I've noticed it available as lets-play on youtube & my review in that case would be:
Cool music, which sounds quite exciting even after some levels. Maybe after passing an aisle, the player could optionally mute / change its audio?
I like the suggestion of "missles" as syringes and the common "myth" about stocking-up on toiletpaper since 2020.
What could be missing: how about a counter of collectable TP and shooting-missles for each aisle so the player could either defeat more enemies or just save them? If the missles get reduced to zero when passing a level, I'd get info before starting the first one. Why not keep storing them (if enemies get stronger or "mutate", while the player needs to aim with more than just one syringe there)?
The background for each aisle could slightly vary, e.g. either look more damaged or single groceries still left there, like references of that "corona-beer" label or a pun about veggie-people and meat being left or soy-products that noone wants to take xD
I could even like some background-shelves referring to freezers or deepfryer, fridges which stores e.g. pizza but being empty too.
Is the player able to get underneath those enemies than just jumping, more like crawling underneath? Optionally: push your cart (like a boomerang) against enemies, could look quite unique, I guess. Maybe with an strength-bar or arrow that aims its direction to even get higher enemies destroyed?
How about molded TP in e.g. green colour, that got infected by those germs? If the player catched those, he could blink a bit and loosing some of his syringes, while being immune to enemies for some moments because of recently getting hit by them.
I like that the protagonist wears a mask, ever thought of adding an update for recolouring it, like as upgrade for every completed aisle by trading-in some collected toiletpaper.
Or offering a sequel similar to this TP-game, but collecting desinfecting-stuff instead?