They did open up their hardware to other operating systems: they engineered a feature into their secure boot system which allows a Mac's owner to attest (with physical presence required) that they'd like to run a kernel not signed by Apple. That's the door Asahi Linux uses. It isn't there on iOS devices, even those also based on M1.

Everything else you're asking for would require them to spend significantly more money and/or engineering resources on supporting the port, and that just doesn't seem like a thing Apple's senior management would go for.