Neblib on Nostr: a bit late, but if you're still looking would mastodon-archive work for your needs? ...

a bit late, but if you're still looking would mastodon-archive work for your needs? https://src.alexschroeder.ch/mastodon-archive.git

Alternatively there is the mastodon-data-viewer project https://github.com/blackle/mastodon-data-viewer.py and the https://github.com/zero-mstd/mav-z project that work on your export file.

I don't unfortunately have any experience with these.