Freedom -- that's what it is. There are now more and more cases where we don't have to ask for permission.
Unfortunately, as I look around, I see most of the hardware vendors around me as gatekeepers. They prevent me from writing custom code in various ways. Apple restricts access to NFC or their UWB positioning, Supernote Manta does not let me access a bluetooth microphone, the list goes on. Denon at least has an API in their amps/receivers: buggy, but it's there.
Denon is definitely one of the better examples, there's so much expensive home hardware out there that gives you basically nothing. Starting from ACs ending with TVs.
I unfortunately can't see it becoming in any way legally mandated either, just have to hope for a good vendor.
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I think, from a business perspective, they just don't see us at all. We're such a small, inconsequential part of the market that building open, free hardware with code that we can update, change, or alter for our needs is just.. not part of their business use-case.