HA assistant provided in Turris OS contains few patches to support old project called Turris Gadgets and we have no plans probably porting them forward atm… We might look to just adding upstream HA and renaming current one to some other name but that is bigger change and probably will be only part of Turris OS 4.0.
And on topic of Python3, we have 3.5 that is just one minor version older then upstream. Also HA specifies 3.5+ as supported so there should be no problems (not only that but for example Gentoo has still doesn’t have Python3.6 marked as stable). But I see that we have older fixup version, I will create issue for bumping it up but I don’t think that we will be doing that soon.
Edit: Latest point. Python 3.6 is planned to be in Turris OS 4.0 but that version is far off for now.