I have been using various better quality (more expensive) milk frothers for years and happened to see this question and would like to answer it for others. Diplomatically speaking, so-called 'milk substitutes' are not milk and have nothing whatsoever to do with it biologically or chemically. Oat or almond milk is produced purely industrially (artificially) and is basically light-coloured water that lacks pretty much everything (except the water) that makes milk and its health. This means that you can NOT effectively froth 'substitute milk' unless you add special artificial chemical substances. Milk, by the way, also has naturally - depending on the animal and its diet etc. - different amounts of substances. - Depending on the animal and its diet etc., milk also naturally contains different amounts of substances, especially healthy fats, which influence foaming. Some modified milk does not foam at all. With natural organic and Demeter milk, I have ALWAYS had great success with milk and hot chocolate, which also foams beautifully, but with slight differences.

I don't know. I've never tried it.