Even finding usable images to flash was tough on the RK3399 and near-impossible on the HiKey960. Even then, the HiKey960 image I found was pretty unstable (randomly killed processes due to a mysterious OOM) and was contributed by a _forum user_, not the official vendor (they seem to mainly support Android).
What should be kept in mind is that these are essentially phones-on-a-board that may or may not have been shoehorned properly to run a desktop Linux. That comes with all of the relevant baggage. For example, the HiKey960 board will aggressively thermal throttle given that all that comes with the board is a piddly copper "heatsink" that you _glue_ on the SoC.
Unfortunately the Raspberry Pi is the only board that I've come across that offers a sane GNU/Linux experience in terms of software support. The performance is acceptable if you consider that even these 4xA73 boards would still get smoked by a reasonable desktop CPU.