I was able to migrate everything else, so I'm guessing it's up to the instance host to provide that data. I managed to export a .json of all my subscriptions, profile info, etc... so I guess it's just a structural issue with how images and posts are shared.
Can't complain about lemm.ee as a service though, they've been upfront about the whole thing.
I'm currently using Win10 IOT LTSC on my main gaming rig, and Mint on my laptop to get used to the environment (started 2 years ago). It's a great way to both get used to the new ecosystem, and have a fallback cushion if some software or scenario doesn't work properly.