Managed to resume my GMail backups after a 4 year hiatus, using gmvault.
The author created a docker version, and I was able to resume where I left off.
Now I want to set this up for my wife as well, but I will have to use a separate container. Each container runs it's own set of daily and weekly cron jobs to backup the emails. If this works correctly, I should look at what they do so I could use that approach for my personal projects.
I am also taking Monday to Wednesday off for vacation, we are driving up to Collingwood this weekend.