Backing up all app data.

An alternative if you are using Graphene would be to build your own image with the changes that you want, without or without root.

Because my new phone would be my new phone. And a phone is a computer. That should be enough of a reason.

I'm quite surprised people who post here don't get that. I've been lurking for years even though my account is new and even though general hackerishness here has gotten a bit reduced over the years, but it's still HackerNews, not ConsumerNews. No offense implied - I just hoped I'd see more people willing to claim their right to own and modify their OS like a true hacker.