If you aren’t married to Hugo as your solution, I will recommend giving Eleventy.js a look.
It’s a static-site generator, but a good amount of flexibility is afforded by virtue of using pure JS to generate view data (which means that you can do any conversions needed, manually or with NPM packages if needed for more proprietary data formats), and it supports a bunch of templating engines too.
I was about to reply with a “oh, really? Whoops, I maybe should I have looked a little deeper” and edited for the post title, but I’m not so sure, looking into the first link you posted.
RE: phabricator…I don’t know what that service is or is for, so I can’t comment if there’s any proof therein.
But the “how to submit a patch” page linked has a section that seems to at least suggest that their Github repo is now first-class, per the first line of the section.
I’m glad it is now. I remember a decade or so ago, I wrote an APNG decoder, so I was deep in the world of APNG.
And I remember reading various things that made me think MNG was the ‘more official’ flavour of “animated PNG”, and it was absurd to me, because APNG seemed like a much more approachable spec. I’m glad the winds have turned…