There is no workaround, sorry. PowerApps cannot edit itself and add code then republish itself.
As an example, here is how you can see that a column name must be a text literal (exact reference to a column)
In this app example i placed a button that has on its onselect UpdateContext({showColumnName:"Title"})
Now even though I have set a variable to the name of the column I want , the gallery can not reference this because it is a string, not an actual column. Easiest way I know how to demonstrate this honestly.
Unless you add it, it won't be there same applies to the datacards forms etc
