No. Toner and setting spray are two different things, two different steps, and not interchangeable.
There are also different kinds of toners: exfoliating (with either AHAs, BHAs, or PHAs; typically you use these a few times a week in your nighttime routine), hydrating (sometimes known as essences; can be used every day, either morning or night), and astringent (think witch hazel toners). Toners are used after cleansing but before the rest of your skincare.
Setting sprays set makeup so it will last throughout the day, and they're used last in your makeup routine. While they may have skincare properties and ingredients, most of them aren't skincare. (Seems to me the only probable exceptions would be MAC Fix+ and Make Up For Ever Mist & Fix.)
Setting sprays focus on keeping your makeup in place. ... While a facial mist can be used as setting spray sometimes, a pure setting spray cannot be used as a toner and is not really a skincare product.
No, you can't. A setting spray is ideally applicable to seal the makeup, while a toner helps hydrate the skin after removing the makeup. Atoner is a post-makeup product that you must apply on your skin after you’ve removed all your makeup from the skin and cleansed it properly.
Toner is usually used to balance the pH of your skin though there is hydrating, exfoliating toner too, that's another story. If your mist has some of the ingredients like Glycerin, Rosewater +witch hazel, Butyl glycol, and panthenol. You can use it as a setting spray or more I should say hydrating binder spray. It helps your makeup to look less cakey. Though it'll not serve your makeup to last long, these are only for a healthy-looking, hydrated, well-bound makeup look.
If you are searching for a fixer that will make your makeup last long you have to find a solution that has polymer dissolved in alcohol, so that when you spray, the alcohol evaporates and the polymer droplets come together to form a layer or film to hold your makeup in place and make it less water-soluble that is waterproof.