From our experience Flutter apps are easy to start with but quite hard to maintain. The core system keeps changing so much you are constantly having to fix things and dealing with broken dependencies. Would never use it for anything important.
Obviously there were a lot of friction when moving out of GetX, but upgrading things have always been easy. Usually at most one day worth of work (worst case). We don't upgrade as soon as a new flutter version is released. We give it a month at least and then upgrade.
During upgrade, most of the problems usually come from 3P dependencies which interact with native such as package info plus. Also, we don't add dependencies unless we really need to. I think we are at ~30 total between all modules.
On the other hand, our react projects are forever in dependency hell. Much larger project, yes but way too many dependencies and too many things break during upgrade.
I think this is the trick. I've worked for a client whose coding standards basically forbade 3rd party clients. Turns out, it often is not needed at all. Do you need to include a library for a bar chart? No, a bar chart is often just a bunch of rectangles and labels.
When you have stupid-simple project setups, you can have huge projects but they'll compile fast and upgrade quickly.
This was years ago, maybe things have calmed down since then, but Expo always felt like hanging onto the horns of a bull, so long as you didn't fall off it was a fun ride!