The problem with this is trust. If you could seamlessly migrate like this, there’s nothing to stop someone faking a long post/comment on their own instance, making them look very legitimate and then migrating that account to a trusted/legitimate instance.
Then using that for spam/selling block chain etc.
People are the reason we can’t have nice things.
I am typing this comment on a Pixel 7. I have had it for nearly two years and I have never experienced these symptoms.
The only app I can think of that doesn’t load in under a second is Asphalt Legends - and that’s because the app takes a week to load on anything.
I am very satisfied with this device, and doubt I’ll be upgrading to Pixel 9. I have no reason to upgrade.