We’re likely talking about a small subset of users for whom open sourcing or similar efforts would be worthwhile. The bigger issue these days is that phones aren't designed to last. We've seen this trend ever since batteries became non-removable, and I doubt EU regulations will make a significant difference. Most users either dispose of their phones when they stop working or trade them in for a newer model. This is especially common with premium phones, while mid-range models might only fetch you $10 on a trade-in if you’re lucky.
Some companies do better in this regard. For example, Samsung provides four major updates, whereas the last mid-range Motorola I owned only gave me one. By the time I receive the fourth update on my current phone, I'll probably be dealing with bigger issues, like the battery not holding a charge—or worse. I wish phones were more serviceable, but that’s just not the case. Still, at mid-range prices, I’m fine with replacing it when it’s on its last legs.
If you're inclined, though, most Android phones allow you to unlock the bootloader and tinker with the software as much as you want.
Some companies do better in this regard. For example, Samsung provides four major updates, whereas the last mid-range Motorola I owned only gave me one. By the time I receive the fourth update on my current phone, I'll probably be dealing with bigger issues, like the battery not holding a charge—or worse. I wish phones were more serviceable, but that’s just not the case. Still, at mid-range prices, I’m fine with replacing it when it’s on its last legs.
If you're inclined, though, most Android phones allow you to unlock the bootloader and tinker with the software as much as you want.