This is sometimes called "the right to interoperate", similar to the right to repair movement. Unfortunately it has been less successful than right to repair so far.
How do you propose to convince appliance manufacturers to all use a freely accessible, standard interface without mandating it via legislation? It's been decades now, they're not going to do it of their own volition.
https://www.eff.org/deeplinks/2020/07/legislative-path-inter...