I would have a gander at the OMV image I have created. sounds a bit pompous its just the radxa 4.4 build with OMV installed where I have worked out a few packages to install and also remove.
https://1drv.ms/u/s!AocmAh35i26QiR-EAvY_MCIaT_eV
Linux 5.2 got released and the new version of mesa is tomorrow so you will prob have the next pre version of Manjaro that will hopefully include PCIe. So at the speed those guys knock out updates if not tomorrow its likely just to be days.
They have KDE, LXqt and there should also be a Mate version on its way.
PS with the above I forgot to edit #intfc:dtoverlay=pcie-gen2
Doh!