Try focusing the URL bar in Firefox and prefixing your query with '%'. https://support.mozilla.org/en-US/kb/address-bar-autocomplet... shows more prefixes like this. It does not search the content of the page, but is super useful still.
I'm baffled how firefox hasn't figured this out yet
In related issues, I'd like switch to tab to be consistent so that ctrl-clicking on an awesomebar result always opens it in a new tab, instead of depending on whether it found a tab or not.
This is terribly unfortunate, given that there are many active bugs associated with this: https://bugzilla.mozilla.org/show_bug.cgi?id=1479858 https://bugzilla.mozilla.org/show_bug.cgi?id=1500991 https://bugzilla.mozilla.org/show_bug.cgi?id=1538069
I've read the thread you linked and I still don't understand their reasoning for this.