INDI packages is found in PPA UBUNTU repository sudo add-apt-repository ppa:mutlaqja/ppa, but if it is not based on Raspbian, where are located the packages?
AIUI if you aren't using a Ubuntu based system then there is no repository, you need to compile from sources.
IIRC AstroBerry at least doesn't recommend this because it may mess up the AB install which could be older than the current souces. They see themselves as providing a stable system rather one that has the latest bells and whistles.
I run plain Raspbian and use AstroPi3 to manage installing or updating the Astro components.
Not sure what benefit there is to the multitude of dfferent flavours of Linux and different UIs and distributions. Looking at Ubuntu Mate and Raspbian the differences don't seem to be more than cosmetic.
I think i've heard that the Raspbian distrbution isn't suited to other people hooking into it and the Ubntu one is better in that respect.
This is also not true, there are raspbian repositories for both SM and AB, you update and install just the same as you did on Ubuntu, the authors of both have created the repositories on there own servers for this purpose, so the end user see no difference....
Once you have purchased SM, you download the image from your order page, and burn to SD card, then you just run the usual update and upgrade commands from terminal as you would on the Ubuntu editions...
I am not a coder at all, so my knowledge is limited on that subject, bu I assure you SM and AB are raspbian based with there own repositories....