It is 2017. Pick an average PC from 2007 and install a minimal GNU/Linux based operating system. You will be able to do basic computing tasks (eg. surfing the web, reading E-Mails, listening to music, chatting) just like on an expensive modern PC. You will even get security updates, so your old computer is protected, just like as a new one.
postmarketOS (I love the name) aims to do the same for smartphones. A small Linux distribution with a phone interface, designed to be easy to update and maintain to solve the problems Android poses in this area. The project is in its infancy, so it needs a lot of help to further realise its vision.
This is a great idea, and it could breathe life into devices not even LineageOS can keep alive.