We need a way to specify just some columns in a $select statement. Today when we use the List records action all of columns are retrieved and it is very bad for performance and we get a lot of information that is not necessary for the flow actions.
If you have more than 10 calculated fields on an entity the "list record" action won't work, becauses it gets all the fields from the entity and cannot get more than 10 calculated fields.
Your Idea would solve that problem. Today only solution is to use the Azure AD HTTP REQUEST action with a GET statement to limit the number of retunred fields.