-I haven't found a way to change the default app icons, but it doesn't bother me that much with all the other apps I end up having.
-the camera app is plenty good for general use. I don't use it for social media or anything, I use mine for work for taking pics of machinery and I use it to take pics of my kids and stuff and it's plenty good for that. I can't say how much tinkering it let's you do, someone else will have to give more detail
-Battery life is plenty good for me. I have a pixel 6, and I go to bed with it at like 45-60% most days. I'm sure the newer phones are a bit better, but can't say for sure
-I wish I could give more detail on the sandboxed apps, I use a few apps that use google play services and they work well, bit idk how it works behind the scenes
-honestly it just works like your phones OS should, it's really quite good
- I also try to use organic maps when I can, but it is still missing things, I use google maps in my browser, but that's getting worse and worse