@linmob @Blort @martijnbraam Martijn also mentioned remote postprocessing some time ago, which makes sense too - my laptop does in 4 seconds what my phone does in 30.
The hard parts are there, what's left is some simple glue. I'm trying to encourage people to do this kind of nice entry-level tasks. Writing glowup.py took me just a few hours of fiddling with libadwaita in total, which would be better done by someone who'd like to learn this stuff and actually take it somewhere further.