You can save this flow and head over your App. The PowerApps part. I created an example app in PowerApp. It has a Database icon that loads data into a collection.It has a gallery that lists the data in the collection.It has a combobox where users can choose an item from the collection and gets its DefaultSelectedItems from the selected item in the gallery, through a context variable.
The Column1 is the same as the name of a column of the table where I want to add the blank row. The [] means there is no value. However, it did not work. It did not create a blank row. Please note I do not want to create a blank table with all the column fields because the column fields may change so it will not be sustainable.