> I'm okay with that if the manufacturer doesn't remove features in bad faith

Again with the abstract. Provide an example of a manufacturer removing features in "bad faith." It is very likely that what you view as a "bad faith" action actually has a reasonable explanation from the manufacturer's perspective. This is especially true in cases of chain-of-trust and anti-tamper protections.

> I never stated that I own the intellectual property but I'm stating that I own the device and such

Technical specifications, datasheets, and similar materials can also constitute intellectual property of the manufacturer. Without access to these, you may not be able to "do any modification I see fit," especially when phrased so broadly that it could mean almost anything.

The only option I can see being somewhat feasible is for manufacturers to eventually release APIs with closed-source binaries, allowing users to create their own applications or operating systems.

This would, however, require regulation to ensure that manufacturers are allowed to provide these interfaces, as in some cases even the APIs themselves may be considered intellectual property, and manufacturers may not always be legally allowed to disclose them. Although it could be argued that if this is regulated, manufacturers would select vendors that can meet these regulatory demands.

The other issues to resolve here would be anti-tamper and chain-of-trust concerns that could arise from such an approach. However, if there were no expectation that users would continue to have access to the manufacturer's software or services, I think these issues could be resolved.