That should work well for apples if you get moist sawdust around the limb it will root without having to ring the bark. I would like to try this with pears chestnuts and persimmons this year. I’ve tried air layering once before and it’s more work and harder to do than I thought. This isn’t a preferred way to propagate apples or pears because most people want a certain rootstock but I don’t think that really matters for habitat purposes. There is also a tourniquet method to air layering as well might look that up if you are interested in air layering it’s a good read anyways.