I build something to visualize huge amounts of email (such as from Gmail) some years ago:
Is there a size option too? To see which senders are using most of my storage.
(Also your website's SSL certificate has expired.)
Funnily enough, the gmvault.org domain _that_ page points to is simply a parked GoDaddy placeholder. It's also not been updated in 10+ years except for two non-source files.
On the other hand, qdirstat "cache" files are really easy to generate so can be used for visualizing a bunch of file-like things