Is it possible to open multiple instances or split view of chrome developer tools tabs?

You can view 'Quick source' while viewing the Network panel (or the other main panels) at the same. This will allow you to view the source and add breakpoints.

However, it's not possible to step through code using the debugging in the split view. Chrome will automatically switch to the Sources tab if you use the shortcuts.

It's also not possible to have an extension running a separate instance of the debugger as the Chrome Debugging Protocol doesn't allow simultaneous clients to be connected.

I will open up a discussion with other Chromium contributors into the feasibility of sharing the debugging controls in the split view. I don't know whether it will or can be done easily. I suspect it's a fair amount of work.

If you would like to set up the split view, as it's useful anyway, go to overflow menu on the right side and select 'More Tools' and then select 'Show console'. This makes sure the panel loads below the main one.

On the left side of the panel that shows, click the overflow menu and select 'Quick source'.

You will now see a small Sources panel.

This is now possible in Chrome 87. Right click Network in the menu and select "Move to bottom"

and it will do this