I notice you're right-clicking three times, and then pressing Ctrl-C to copy; is left-clicking to select and then using the keyboard shortcut to copy not feasible in the software you are using?
What may be more efficient, if the target application facilitates it, would be to copy the contents of the entire column, rather than checking each cell individually.
In applications like Excel and Google Sheets, selecting an entire column can be done using the Ctrl-Space keyboard shortcut, though this may not be available in your target application.
If it is not, you can try selecting the topmost cell of the column, then using the Shift-PageDown to select all items in the column.
If either of those allows you to copy the contents of those cells, preferably as text (if you can paste into notepad and the contents of each cell are on their own line, that's ideal), that data could then be used to look up which cells are available, and at which indices.
Using an inline function to split the newline-separated list would likely be the simplest method to process that data.