Local bookmarks need an offline cache that at least contains the text content and headings of the URL. Otherwise, the search will stay useless because nobody can organize them manually without making (human) mistakes after a while.
Ironically, Chromium's omnibar search worked by searching through headlines for a while; but meanwhile it's broken again, and it never worked for bookmarks and only for history entries.
When I open a new window[1] in Firefox and start typing in the address bar, I get matches based on the page title not just on the url.
For example, I open a new window and type "brow" and the matches I get include "I closed a lot of browser tabs | Hacker News" (see image[2].)
So I rarely if ever use bookmarks, I can almost always find what I'm looking for by typing in the url bar, or if that fails by searching in history.
1: Are you seated? Good. I don't use tabs, I just open new windows with ctrl-n and use alt-tab & ctrl-w to navigate. I have middle-click set to open in a new window. I use customise to put the "open new window" icon onto my buttons, next to the address bar. I would happily use a version of firefox with no tabs, they add nothing to my life.
Note that ctrl-shift-N opens a new window.
As does ctrl-n, which I mentioned in the comment you're replying to ;-D
The omni-bar reinforcing past browsing habits that were formed out of addiction by putting them in the top of the suggestion list is a dark pattern for me.
Another convinien search shortcut is ^ (for history) and % (for open tabs).