The package xAct does something really nice when it handles Large outputs, which is to represent the expression as a symbol and display that symbol when the cursor hovers over it. For example

<< xAct`xCoba`
m = DefManifold[M, 4, {a, b, c}];
ch = DefChart[chart, M, {0, 1, 2, 3}, {e[], r[], t[], q[]}];
$LargeComponentSize = 1;
CTensor[{x + y}, {chart}][\[Mu]]

The expression x+y is mapped to a red symbol, which displays the expression when you hover the mouse over it. I've been trying to figure out how to do this natively in Mathematica but have been unsuccessful. I've tried using Iconize, Short, and Shallow, but these dont achieve what I want. How can I do this natively without utilizing any packages?

Thanks