I hear you!
I do not think it is possible.
What I opted to do is to have yes/no groups in a hidden popup and name them along the lines of the condition that I am dealing with. Build the longer expressions there and use them where needed on the rest of the page.
name of the group: var - is the thing empty?
“long” condition: current user role is app admin and count of things is zero and page name is admin
group type: yes/no
group data source expression: search for things :count is 0 and current user’s role is app admin and page name is admin
Then I use “var - is the thing empty?” in the actual place I need it (an action or element)
It helps me with understanding the logic in a much easier way and I just “shrunk” the long-composite expression.
And it helps with having to go back to edit all those long conditions when a major change is happening in the app. Those long conditions are now shorter and thus editable in an easier way.
Hope the above makes sense