In Chrome, you can add a new search engine.
Name: Bookmarks
Keyword: bm
URL: chrome://bookmarks/?q=%s
Then, you just type bm test for example in the address field and press enter to search your bookmarks. Doing it this way won't search as you type.
But, this doesn't seem to work in Opera as the opera://bookmarks page doesn't support a ?q=something or ?search=something.
In Chrome with the chrome://bookmarks page, if you:
Click in the address field (which selects all text).
Type your search term.
Ctrl + a to select your search term.
, you can drag the selection to the bookmarks search field and it'll avoid searching as you type. When you drag, the address field drop-down will disappear for you so you can see the search field.
That doesn't work in Opera either though. The bookmarks search field won't accept the dropped selection. Also, the address field drop-down doesn't disappear when you drag. You have to press esc before you drag.
For Opera, you could try an extension like https://addons.opera.com/en/extensions/details/bookmarks-manager-and-viewer/?display=en. It searches as you type, but maybe the search will work better/faster than Opera's. Or, maybe you can find a different bookmark extension that works for you.