So, get an external battery pack and a long cable. I have one for emergency power outages, but it is perfectly usable to keep an older phone going. I prefer replaceable batteries, but the market is apparently moving away from them.
That can definitely work, however the micro-usb and even Thunderbolt (Apple style) connectors will fail after repeated use. Granted “repeated” means thousands of times, but when folks are keeping phones for 4 or more years, this failure does occur often on a long enough timeline. This is why I purchase wireless charging phones, which most of the newest models now support, and keep a wireless charging battery in my backpack.