Chrome allows this customization by having a menu option for focusing the URL bar("File -> Open Location..."). This defaults to Cmd+L (like Firefox) and you can customize built-in shortcuts natively ("System Preferences -> Keyboard -> Shortcuts -> App Shortcuts") on MacOS. With Chrome and Brave I've simply switched around Cmd+D to "Open Location" and Cmd+L to "Bookmark This Tab".
I assume this (a simple menu entry) would be a trivial addition? The lack of this is in fact the only reason that keeps me from switching to Firefox (I love containers). Using Alt+D on Linux for years and later Cmd+D on Mac has made this deeply ingrained in my muscle memory (I keep my thumb resting on Alt on Linux and Cmd on Mac by default).
Cmd+L sucks since it requires me to either use two hands or switch to use only the right hand - which usually rests on the touchpad - resulting in quite a jump. I know F6 works as well but that's also a two-hand operation (since it involves the Fn key).
This would enable me to finally contribute to the fight against Chrome's browser monopoly. 🙏
 I have tried various add-ons as well as modifying omni.ja, all without success.
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Seems like it would be low-hanging fruit to implement, but this idea still might not get enough traction.
Would I get notified if the status of this changes (to "In review" or whatever)? Or do I need to check back here (or try Firefox) every now and then?
I would DEFINITELY like to see this feature implemented. Would be very nice to be able to use "Control-L" instead of "Command-L"! Thanks.
FWIW, I was able to make Cmd+D focus the address bar by using BetterTouchTool to emit Cmd+L keystroke when Cmd+D is pressed. Works like a charm.
@joelptis that tied to Firefox only? Because otherwise it'd mess up Cmd+D for other apps (like Chrome that I have natively remapped).
I worked around this using Alfred, creating a Workflow that only applies to Firefox, which does the same thing - sends a Cmd+L triggered by Cmd+D. By default it's a bit slow, there's a clear lag, but there's a setting for the trigger hotkey, "Trigger behavior", which when set to ""Pass through modifier keys (fastest)" feels instant/native.
So for the time being this is "solved" for me. There's however no way to make Cmd+L bookmark stuff (since that would create an infinite loop), but I can live with that since I don't use bookmarks. Ideally there'd be a menu entry (as per initial description) so that this could be natively mapped.