I recently tried using sxmo, a lightweight configuration of dwm controllable via pinephone buttons and the touch screen combined with some command line+dmenu scripts that allow you to do many common tasks (including calls/text) all from the terminal. I was really impressed at not only how efficiently it runs, but also how intuitively it controls despite being a simple window manager. I think this really has potential for being a go-to “lightest” Manjaro distribution for Pinephone: sr.ht/~mil/Sxmo/
I was able to get it running by building on a phosh manjaro image, but it could definitely use some love to include more apps, scale them properly like on other versions, etc. Please consider this as an option for a new flavor of Pinephone Manjaro! 
Never thought that the desktop environment of a device that basically has touchscreen as it’s only input is handled so well with only 3 buttons!