(disclaimer) No itention to make a Frankendebian (https://wiki.debian.org/DontBreakDebian) but ubuntu package "zram-config" works perfectly.
I tested it for two weeks in a: Orange PI Zero 512MB Armbian Stretch 5.40 4.14.18, Orange PI PC2 Armbian Stretch 5.40 4.14.18, AMD Sempron microserver Debian Stretch 9.4 4.9.0-6-amd64.
A short tutorial:
1. Download zram-config package (it's a universal package, it does not matter the architecture in use)
wget http://de.arch