Also need replaceable batteries or atleast some standardized Li-Ion flat packs
Then we can stop tossing entire phones in the garbage.
I have a Pixel 5. The Pixel 7 isn't even an improvement to me. The fact that my battery is at 15% after the day is done means I am on my last year with the device.
I have a Nexus 6 with basically no battery to speak of but it works great still outside of that.
So for my second suggestion, if a company claims to be focused on climate change reduction, using a non-removable battery will double the tax.
All proceeds go to renewables for whatever state has the best(lowest) carbon footprint not yet at 0.
Let's see how long the "thinness" of the phone matters.
There are still legal issues, mainly that the manufacturer does not provide replacement parts and aftermarket ones infringe on manufacturer's intellectual property so you only get ones produced in shady chinese factories and good luck importing them in bugger quantity. What really needs to change are the IP laws so that --when manufacturer fails to provide replacement parts or charges outrageous price-- the IP becomes free-for-all shortly after the product release.
Much bigger problem are blatant anti-repair practices - be it kindle buybacks, sonos "brick your old device to get a discount for new one" or manufacturers pairing parts to the device (looking at you apple) so that the parts refuse to work due to a software-lock. Additional tax or even hard penalization of those practices would make sense. Also it would make sense limiting the reach of DMCA and IP laws to enable users to "break digital locks", modify and distribute modified firmware in order to bypass those arbitrary restrictions imposed by manufacturers.