I’m assuming you’re making a tincture and not a topical. Your understanding of nano emulsions is correct because they do indeed break things down into smaller parts but the thing to remember here is that in “breaking down” it actually encapsulates your target molecules in some way. So it basically creates a bubble around the THC or CBD. This bubble will then allow the cannabinoids to pass through barriers it typically would not be able to pass through as easily thus upping the amount absorbed by the body. The trick to getting an emulsion to stay is formulating with the right ratios and homogenizing effectively. There are emulsion blades that you can purchase to help with that second step but when trying to mix water and oils they usually want to separate making it tricky to keep an emulsion for extended periods of time. shaking the bottle of tincture before ingesting is always a good idea.
As far as a formulation goes I would start by dissolving your RSO in oils (MCT and Sunflower are my favorites), then adding some Ethanol and finally water to help create your emulsion. The ratios are going to be key in getting the right emulsion to happen. Keep notes and start small scale on everything!