Brief Summary
When executing the shortcut for copy current URL, it is a tad bit annoying that there is no indication of whether it happened or not. I am sure it works every single time. But the lack of immediate feedback makes it an incomplete feature in an experience standpoint.
A minimal visual feedback by any means would be awesome.
Very Abstract Possible Solution
p.s. don't judge me 
I was searching for which existing elements can be used for this purpose. This is just a blind idea since I don't know what mechanisms are used here to implement this. So I hope that you can display a blinking copy icon on the url bar in some convenient place when executing this shortcut. I saw the reader mode icon becoming visible on the address bar when hovering near it. maybe something similar I guess. I might be totally wrong. Or I don't know how the hovered link display at the bottom left works, maybe rework into that I guess. Or just send a notification to system.
is up for discussion. I think this is the best way, although in the Mac/ Orion style rather than Arc's. Similar popups can be implemented for tabs opened in the background, closed all other tabs, and so on.