While I totally support such legislation (even for current sold devices, not just deprecated), there's a massive pile of android devices with open bootloader which never got any decent second life support.
That shouldn't stop the regulation from existing, but yes, maybe another regulation in a similar way for forcing companies to open source drivers and bringup code after N years of the release?
Those might be niche devices, I think if were Samsung or Pixel devices, it would be a different story, similar for Apple devices, they are fewer variants, that it would be a lot of developers putting effort on adding upstream Linux support if they were open, like is happening with the Macs with the M series.