I commented to the wrong ticket, but resolution is: https://phabricator.wikimedia.org/T404557#11487366, repeated here:

The WMCloud instance was again maxed on disk usage. I found the root cause of that though which was that the Docker images we are building to package the code were never getting pruned, so there were over 10G of old images hanging around. When Docker does a build of an image that has changed, it will hold onto the past versions until you explicitly remove them. The manual and common solution is simply to routinely run sudo docker image prune. There may be a setting you can set on that servers Docker configuration to make it auto-prune routinely, or one could simply create a bash script added to a cron schedule to do this for you... Not sure what is best or standard for that, but for now we're out of the woods with disk space usage and just run that command going forward.

However ever after clearing up the disk space issue and rebooting everything I was not able to get things working again. The backend still seems to not be happy and the data isn't pulling. The backend is the issue, and it appears to come up fine accordingly to logging but isn't showing up on port 8000.,.. Maybe stuck in some migrations? @RickiJay-WMDE

Yay ! We're back up! After clearing up the disk space issue, I was able to manually kick off all the migrations and that seems to bring things back to life.