Yes, we have the shortcut ^⌘⏎ on mac but not on iOS/iPadOS (unless you use external kbd)
In Ulysses Mac you can use either Tab or Return, and that works much more fluently, and Return on iPhone and iPad which is also very easy and accessible on their onscreen keyboards.
Selecting rows for copy/paste would also really enhance the user experience in Bear 2.0 tables.
In Ulysses, Tab moves to the next cell but creates a new row if the selected cell is the last one of the last row. I think this is something we can consider adding.
Regarding iOS and iPadOS (without kbd) we provided (Panda for reference) a way to move inside the table within the custom table keyboard (BIU button).
Adding a menu item to the … menu on the cell seems a good solution for copying a single row but I don’t know if you meant copying 1 row or more. Also, please tell me more about your use case for this.