A cheap phone last about as long and does 90% the same stuff

This is true. You can get an almost equal performance out of a cheap phone. But I learned that more expensive or high-end phones recieve more software updates than cheaper entry-tier phones.

For instance, I own an LG K8 (Model LG-M200E) from 2017. The battery still holds enough charge (although it is designed to be replaced), the camera works, the touch display still responds properly - but it only recieved one update (Android 7 --> Android 8) in 2018. I wouldn't consider it secure and I certainly don't have my online banking on the phone. Meanwhile it gets very hot and slow when I use Google Maps. Unfortunately, there is no way to replace its operating system with an alterntive OS, linke Grephene OS or Lineage. None of the many alternative operating systems offer suppert for this specific model.

My next phone will propably be mid-price ranged.

Edit: typos