I think a better idea would be for all public toilets to be a self-contained and insulated unit. Once someone leaves, a high pressure flood of hot water from the ceiling washes everything followed by a blast of air to dry everything. Obviously, the toilet paper container would have to be water sealable by auto control for the duration of the cleaning operation.

That's surely going to sanitize the toilet, but it takes an enormous amount of energy to heat and pump water into the stall every time a person uses it. For the sake of energy conservation, a little sanitizer spray would work fine.

A beam of intense ultra-violet light focused on sensitive areas might be more economical and practical. If the light functioned only when the booth were unoccupied there would be no danger to occupants.

I ate at a wonderful BBQ Restaurant that had a spray sanitizer. You spray some paper with the sanitizer, and wipe down the seat. I say it was a wonderful place to eat because of the latest technology in seat hygeine.

Onus should probably be with the house. My old workplace left out a full-sized can for whomever wished. Could also consider wet-wipes, like some grocers do for carts and baskets.