I've got a Nexus 7 2013 and I was wondering if there would be any development for small tablets... and I'm not a developer sadly...

I'm really interested in Plasma Mobile

I'd be interesed in a Nexus 9 Version very much.
Although, I am currently a Little afraid of rooting it, as my previous N9 would only Boot up after rooting, Just to Reboot again ....

Im also not a Developer, and as far as I know Plasma Mobile's UI works fine on tablets, but there aren't images provided for now, and you would have to make your own. Or if you have a tablet which runs on an Intel x86 platform, you kould try installing this kubuntu-based image, but it's really outdated. http://pangea-data.s3.amazonaws.com/mobile.kci/images/20151124-1541/kubuntu-pm_201511241541-amd64.iso This Iso image will also work on your PC or Notebook, but it's much better trying it on a touchscreen.
Building your own images and do porting yourself is complicated, but here are a few porbably helpful links:
http://blog.bshah.in/2016/05/02/plasma-mobile-new-base-system/
https://github.com/plasma-phone-packaging/cm