I recently bought a Chromebook with an ARM processor and the battery lasts around 12-15 hours. It's a huge upgrade from my 10 year old Intel laptop which did 2 hours at best. I did try replacing ChromeOS with proper Linux but it's too complicated and I gave up. Moreover, ChromeOS isn't that bad, it's looks very eyecandy out of the box and has a lot of fun features - including Android app support. I always keep it on battery saver mode though.
The next challenge was to get my Flutter dev environment to run on this. Here's how I managed to get it running, without compiling anything from source.
1.1 Install basic and Linux build dependencies mentioned on https://docs.flutter.dev/get-started/install/linux/desktop:
$ sudo apt install curl git unzip xz-utils zip libglu1-mesa