First let me say that lots of additives are safe and improve greatly the odds of you having an excellent wine! Yeast nutrients for instance prevent failed fermentation and avoid rotten egg smells. Pectic enzyme breaks down pectin and helps your wines clear. Great products! I wouldn’t skip either! K-Meta is a great tool when used correctly! but let’s say you are just set on doing it without all these great products for whatever reason, let’s talk about making wine without them.
If you use wild yeast, anything can happen but usually, fermentation is successful. It’s been done this way for centuries! Cultured yeasts though, just so you know are wild yeasts harvested from great wine regions where they’ve been naturally. We’re just lucky that someone captured and cultivated them for us! But if you want to skip adding cultured yeast your wine will still probably ferment, usually enough to call it wine.
So we’re starting out with fruit. If it’s grapes there may be no need to add sugar as wine grapes produce all the sugar you need. Mash them and then either cover and leave them or press and just keep the juice. Within a day or two it will be foaming, probably with a reasonable yeast that can both start and finish the job, maybe one that will make excellent wine! If you’re using just about any other fruit you may need to add sugar in some form to produce enough alcohol to preserve the wine.
Step feeding: To avoid having to stabilize the wine you can step feed, add a little bit of sugar every day until the yeast dies from alcohol toxicity. It varies a lot what % the yeast will die at depending on the strain of yeast. some wild yeasts will die at 5% alcohol, too low to preserve the juice or even call it wine technically. Others may reach 18% or higher. In any case, feed it sugar until the yeast dies. When you’re certain it’s dead (if you don’t want to use a hydrometer to measure best of luck!) then you can sweeten a little more if you think it needs it and it should be safe to bottle. It would be smart to bulk age it, racking several times, to avoid a lot of sediment in your bottles and also to be sure some other wild yeast doesn’t mosey by and re-start fermentation!
If you successfully got it this far you can bottle it and have sulfite-free wines! They may be the best wines ever or not, depending on all kinds of things beyond your control. I’ve done side-by-side batches of wine, same red wine grape harvested the same day and split, half on wild yeast and half on cultured yeast. Whatever the wild yeast may have been it finished the job in less than 4 days, the fastest ferment I’ve ever had. the other batch took 7 or 8 days.
Pectic enzyme, for instance is an enzyme that breaks down pectin, the thing that makes jams and jellies set up. Pectin also can cloud a wine and pectic enzyme is the easiest way to prevent that.
Yeast energizer/nutrient just feed the yeast all the things it might not be getting from the fruit and sugar during fermentation, keeps the yeast happy and doing its job, avoids rotten egg smells in your wine.