A carbon embodiment tax is way easier.

The reason we don't have one is the embodied carbon tax would have to be 100,000x higher for a Rivian EV than it would be for a smartwatch, while superficial 20th century environmentalist doctrine concentrates on the relatively negligible portion of "e-waste".

Ideally you will have a different definition of repairability for each category of devices or even per-manufacturer. Policy wise, the problem is the specificity of the legal language/phrasing.

To me the easier approach is to make exclusive supplier contracts illegal in the retail segment. A third party repair shop should be able to buy the same parts as Google and offer a repair service if Google is unable to provide one.