How to implement a "fullscreen" functionality (collapsing and expanding multiple panels at the same time)?

[samesfahani-tuplehealth]

Repro: https://codesandbox.io/p/sandbox/react-resizable-panels-forked-kfqmkl

The problem really is that on the first collapse, we have:

{
  "panel-1": 33.3333333334,
  "panel-2": 66.6666666667
}

When we toggle fullscreen and therefore expand, we expand panel-1 and panel-2 to the above values, leaving us with the layout

layout: [33.3333333334, 66.6666666666, 0]

Aside from it not working like how I would like, this feels like the wrong approach altogether.

[samesfahani-tuplehealth]

Strategy of saving/restoring layouts works: https://codesandbox.io/p/sandbox/react-resizable-panels-forked-lqf99z
Marking as answer.