Homebrewer/fermenter checking in. Yeast is everywhere. Its already on everything. To an extent where homebrewing has a special category called wild or spontaneous fermentation specifically for stuff made just by letting wild yeast settle on it and start going to town. Which is to say that if you’re a bit lucky the only thing you need in order for wine to happen is fruit. Do you know how you make a fermented pepper sauce? Kim chi? Sauerkraut? You just need whatever it is you’re trying to ferment, and some salt. That’s it. The fermentation will just happen. Some small amount of alcohol will just happen.