For everyone trying to port to any other architecture, you may get a glympse from my approach at running zynthian on an allwinner H3 in this thread.
The result of that looks like in this post. I’m still using that build today and it works fine. Though, not all features of zynthian are really 100% usable, and some of them completely broken.
I’m now taking a much bigger challenge of porting it to a completely different distro which details you can find starting with this post.
Note that so far I am running postmarketOS in QEMU(the setup is really easy to do with their build system) with decent performance. It is there that I am now developing until I just recently bought a used Pocophone F1 and waiting for it to arrive 
Anyone interested that can join the effort, let me know. Porting to PostmarketOS will imply being able to run zynthian on multiple phones with minimal adaptations(hopefully).