I am still very interested in refreshing the images for the Raspberry Pi.
I’ve had a lot going on with my family over the last 6 months or so and a few things had to give, one of which has been working on the Pi images, by comparison, the GPD Pocket images took just a few hours to make.
Starting 29th October I will have the capacity to work on refreshing the images for the Raspberry Pi 2/3/3+ and I welcome the involvement from any community members who are interested in collaborating 
Planning for the new Pi images starts today and something I will flesh out next week.
I want to introduce a change of direction with regard to how the Pi images of Ubuntu MATE are produced. My thoughts are aligned with what @stillwinter has suggested, and I’d like to make a “real” Ubuntu using the Ubuntu provided kernels rather than the hybrid I’ve created in the past.
I’d also like to dodge the massive effort of side-porting a heap of Python modules and applications in a PPA, that is a massive time sink. My feeling is that piwheels/ can solve the Python module requirements and I’m already working with the Raspberry Pi Foundation on creating Snaps of their prefered applications. So a future Ubuntu MATE for the Pi would effectively be a vanilla Ubuntu MATE with minimal modifications to tune it for the Pi. VLC will not feature in the Pi image, preferring instead tomxplayer from @Meticulus.