One thing I do is check before buying the phone that battery replacement is not too difficult. Looking on ifixit.com and web search for “battery replacement model XYZ” both find good info about this.

I’ve given up on looking for phones with swappable batteries (they almost don’t exist any more) but a phone where you can do a battery swap with a few simple tools is far better than one where you have to perform delicate microsurgery. Then just accept that batteries are consumables that have to be replaced once in a while.

The fact that we have threads and articles about prolonging battery longevity is a sure sign that the sealed internal battery is a technological failure if the idea is that it should outlast the rest of the phone. The real idea is of course much different.