I'm still rocking a maxed out MacBook Pro from 2013. The battery IS shot but plugged in and connected to a monitor it still gets the job done as a home machine.
Maxed out Macbook Air 2013 here. Replacing the battery was surprisingly easy and cost about $30. I should replace the SSD at some point too.
It's still getting new MacOS releases/updates using OpenCore Legacy Patcher [1]. Once MacOS is ARM only will put Linux or OpenBSD on it and see how long it goes.
I dont know how comfortable you are with with opening laptops but please make sure there is no spicy pillow issue (expanded lithium ion battery) in your machine because they represent a real fire hazard.
Replacing old batteries is sometimes extremely affordable if you're willing to open the machine yourself.
