As someone who jumped on the ARM train early, and someone who doesn't want to contribute to creating more electronic waste than necessary, it's disheartening to see 32-bit ARM being increasingly ignored as a platform compared to ARM64.
edit: I don't want to take up more space in this thread, but would like to thank Vogtinator and saagarjha for pointing out other options for 32-bit Linux distributions.
The demise of 32-bit was/is inevitable for personal computing.
The last iPhone with a 32-bit processor appears to be the iPhone 5c, last produced in 2015. As I type this on a laptop from 2015, I have to question your definition of "ancient".
If not for the camera and iOS support inevitably ending, I don’t see much reason to upgrade.
One of the kids' phones is an SE which is pretty much the same internals as the 6S and it's still good.