Michael Chare wrote:
These days that will limit you choice. The batteries in the Nokia 6.1,
my Xiaomi and many of the Moto G... phones are not easy to change. You
would need special tools and a youtube video to show you what to do to
change the battery.

There is easy and there is easy. While phones might not have removable
batteries any more (ie tool-less batteries you can swap every day), some
have serviceable batteries - undo a few screws, back pops off, unplug
battery cable, plug in new one. You might need a small Torx screwdriver but
that's it. Then there are the phones that are full of glue and you first
need to heat gun off the screen

It's worth looking at iFixit for their repairability ratings as they tell
you how easy it is to do this sort of thing.

With the previous mobile phones I have had, the battery has to be
removed to change the SIM.

Most phones nowadays have the SIM on a tray that slides into the side. The
battery removal is just an ancient design pattern of 'phone must be powered
down when SIM is changed' which they enforce mechanically by putting the SIM
underneath the battery. They didn't notice you can leave the phone on
charger while removing the battery.

Theo