I installed the GPD image of Ubuntu MATE on my GPD Pocket 2. It runs quite well, but there is the infamous screen tear due to Xorg not being configured properly for the Intel Graphics video card.
I could solve it manually using the very neat instructions provided on https://github.com/joshskidmore/gpd-pocket-2-arch-guide.
I also realized, by checking out the official repository, that pull requests had already been submitted to solve this issue.
I did fork the repo and was able to successfully respin a Linux Mint 19.1 MATE ISO, and the suystem installs perfectly fine and benefits from the tweaks brought to Ubuntu MATE for the Pocket/Pocket 2.
Many thanks to the devs for this, I now have my favorite flavor of Linux running perfectly fine on this neat device
You can check my fork here : https://github.com/nicosensei/gpd-pocket2-ubuntu, the linux_mint branch contains the existing pull requests and my own modifications for Linux Mint 19 (which basically boiled down to duplicating the fixes to the respin script).