In Linux, it is impossible to override system shortcuts - the system gets them before your program. Not certain how Macs handle it - but if they want to be consistent across platforms they need to change it.
I think only Internet Explorer (maybe Edge as well?) has this feature. I believe it's up to the browser how it handles an <input type="password"> control, maybe an extension can do the trick, although I'm not sure if the browser would let an extension have access to a password.