Absolutely, this is a great example where Hister can shine.

I started Hister as a proxy as well, but quickly switched to the current extension based approach, because intercepting HTTPS traffic requires a MiTM proxy which is much more painful to setup than installing a browser extension.

would it be possible to gdrive/rsync/git the data between machines and then use the data on an online server for retrieval (given that I would handle data sync myself)?

also what exactly are you using for search? does it support trigrams? how do you sort results?