Compared to IDE 2.0?
Maybe VisualMicro or VS code; I have no experience with them.
How do you visualise uploading to multiple boards at once? Parallel or sequential? I think that it will boil down to scripting (bash, bat, powershell) of avrdude.
There was a topic a while ago (over a year) where somebody did it for Pro Minis. If I remember correctly, all TX lines of the Pro Minis were tied together which was not the most brilliant solution. But it seemed to work 