The easy option would be to have a default law like "you open source your code 5 years after it was created for phones/tablets/cars/etc and it automatically applies to your suppliers as well and the necessary software tooling to get it working. If this requires hardware to program the devices, provide the blueprints of the devices as well".

Then it would be understood and agreed that anyone making software they have to release as open source what was closed source 5 years back. This way I would say that you can't bring the "but the competitors will use this to steal my business" argument.

What you would get in essence is a snapshot of what technology looked like 5 years ago (or a decent number of years people can agree on) and you can fork from there if there's a will to give a second life to various devices.

But really, I don't want an ugly phone because someone decided batteries should be user replaceable like in the old days. And yes, I like my iPhone to be sleek.