[1a] Go to Products and [1b] click on Filter-button on the right.
[2a] Click on Add new filter and [2b] select Sales channel.
[3a] Select Online channel and [3b] select Excluded.
You see all unpublushed products to online channel.
[5] Click on Include in sales channels.
[6a] Select all channel you need, but make sure to select
Online channel and [6b] click on Include products.}
[7] Cancel the filter or you can save the filter for quick access.