Show taskbar (system tray) icons on all displays

Solution 1:

I believe you need to open the Settings app and then go to Personalisation > Taskbar. Scroll down to Multiple displays, and flick the switch that says "Show taskbar on all displays". Check that the "Show taskbar buttons on" dropdown is set to "All taskbars" so that the icons show on all displays.

I don't think there is a way to get the system tray to show up on all displays. According to Addictivetips:

There still isn’t support for getting the system tray to show up on multiple displays

And according to the second-to-last answer on Microsoft Community:

Currently, having a notification area option for both taskbar is not available.

However, things may have changed since April 2017. There may be a registry tweak or something that you could use? I certainly can't find anything.