Ask HK: Quickest way to develop mobile apps as back end engineer in 2021?

One more vote here for flutter. Dart is not a language I’d want to use day by day but it gets the job done without getting much in the way. Tooling is great and there are a lot of libraries you can use for mobile platforms. Desktop support is a bit behind but is usable. You can also look into something like flutterflow.io to skip some boring parts of ui building. Haven’t used it much but since it allows you to export your code it does make building your initial pages much easier.

I've worked on a production app written in react native for 3 years - if the use case is as simple as you say, it should be absolutely fine. It can become an issue when interacting with eg camera or Bluetooth, bur that's likely to be the case anyway. Expo is pretty good.

Anecdotal of course, but there is a reason react native / expo exist and are as popular as they are.

Kotlin of course for native android. Java is dead for android development… no point in using it with new apps.

I would agree with this if Java / android SDK was as nice as swift.

Currently moving an old Angular+Cordova project into Capacitor...

Capacitor is very poorly documented in my opinion. The official documentation seems sufficient but it has been, at least in my experience, pretty easy to run into edge cases that don't have straightforward documented solutions available, and it's obviously a bit too young to have a ton of StackOverflow answers available, for example.

My understanding is that the Cordova team and community has mostly moved on to Capacitor, and while there is some backward compatibility, it is often not evident to what extent you need to tinker with both to get them to work.

It has to look professional for sure. But the UI won't have anything fancy, only some line charts and few forms.

If you're going with Ionic, do not go down the Cordova path. I haven't tried Capacitor, but that looks like an option now.