After discovering the Select Page A, Select Page B, it gave me an idea for using empty pages to automatically open a full-screen window of a specific AUv3. This lets me dedicate a page to an AUv3's UI. I have next page/prev page mapped to hardware buttons on a Launch Control XL so jumping between pages is very fast.

The only issue is that I need to also close the AUv3 windows when leaving the page. In the template I've made, I manually add closing all the other AUv3 windows to the follow action for each page that opens another one, but you can imagine how that can quickly spiral into being hard to maintain once I'm doing this for a lot of plugins.

Anyways, that's where Leave Page A, Leave Page B would come in handy... then I can just have a follow action for Select Page A that opens a specific AUv3 and a follow action for Leave Page A that closes that same AUv3.

Maybe there would be other use cases too! But that's what led me to the idea.