I’ve fixed the view-only thing and adjusted the permissions so it shouldn’t happen again.
As for making a view-only duplicate, if I can keep it sortable, then I’ll consider it.
I think it might be possible to have a button that resets / updates the copy using importrange, and then instruct users to file->make a copy if they wish to sort the data.
I was looking at this stackoverflow question that sounds similar:
I’m no spreadsheet wizard, but I think it’s worth looking into, anyway.
Also, wouldn’t it be highly disruptive to have someone sorting the editable version while you browse it?