Nested routes do work, but for some reason require <IonPage> as a wrapper. I made an update on that post.
Code splitting definitely works; I have it working in the app I am building on the latest release of Ionic (6.0.14).
As for transitions being triggered multiple times, I’ve avoided such issues by using react-query, <Suspense>, and <IonLoading>. Basically I load the data I need async with react-query and use <Suspense> to show an <IonLoading> component until I’m ready to do the render, which gives me nice transitions and avoids a whole lot of other kinds of errors.
As I said, I’ve found all the bugs I reported to Ionic that included a sample repo got fixed pretty quick, and the ones that didn’t have a repo attached generally got ignored. So the way forward to get fixes is to actually demonstrate the bug and file a formal issue. If all of us take a little time here and there to do so, a lot of bugs will get fixed and we’ll all be much happier using Ionic.