People who liked this might also be interested in Halfbike (https://halfbikes.com), a standing bike which also is reasonably portable. I tried it once and while it does need some getting used to, I like the idea.
I use Recoll[1] to search through my local files. Haven't tried it myself, but they also have a extension for Firefox[2] that does what you are looking for.
Edit: I just tested it, and it's pretty neat! However they note in their Documentation[3] that this is a web cache and not intended to be an archive. It can simply be turned into an archive though by configuring a large cache size.