I'd been looking for a simple catch up script, but all I've been able to find are really old Python scripts that either don't work with "new" Reddit, or only work for Python 2.7, so after trying to get a few of those to work and constantly hitting API or Python3 differences, I figured I might as well just crank out a simple script using Node.js instead (mostly because I wanted to keep dependencies local, which for Python basically means writing a pipenv based project, which makes things super unfun for the casual "I just want to catch up on my images~" users).
It works well enough, to the point where I can just have it run as a cron job every hour and have another util watch its download dir, to move pictures to the dir that my digital picture frame (which is just a monitor and a raspi running "whatever runs feh") loads content from. So maybe others on HN might find this useful, too.