Well of course as any technical choice this is a compromise These are all very valid points, that we did consider, but I think the alternatives were just not as good.
I feel less strongly about apps not looking like system apps; in fact, I kind of dislike apps that try too hard to look like the settings page: I like when they bring some variety, some personality, something that makes them stand out. Though I agree that broken interactions are unbearable, e.g. apps that break the "swipe back" gesture.
It could have been a web app as well (in fact, the initial version was), but some offline functionality was needed, and service workers messing up caching and iOS not being a great player with PWA, it just ended up being more painful than it should have been.
Or we could have built 3 apps, which I would have loved (but we are a team of 3, and working on a bunch of other things at the same time). Flutter does have a fairly good developer experience (its hot reload cycle is unmatched in my opinion), but of course native development, with all the support libraries you get from the platform, is on a different level.
(What even is native though? Is UIKit "more native" than SwiftUI? Is Safari native? And how about the web apps you open in Safari? It's JS code, but at some point it's compiled to ARM instructions, now running from the very same memory pages as Safari, does that make the web app native?)
Having said that, it's not like I need to convince you to try out our app, it's good that we have options and probably Apple Invites is what works best for you!
But out of curiosity, when is the last time you did try out a Flutter app?
Because they have been improving a lot, in fact for quite some time they ran better on iOS than on Android thanks to the new Impeller rendering engine (now default on Android as well)[1]
They did some work for accessibility on Web, too.[2]
BTW it's funny you mention React Native, I last built something with it a long time ago... and it wasn't that good - but I just realised I do use some React Native apps right now, so I guess they also improved a lot; I should give it a shot again!
[1]: https://docs.flutter.dev/perf/impeller
[2]: https://docs.flutter.dev/ui/accessibility-and-internationali...