Honestly, you'll get a lot of varying advice on this topic. Everything from embedded browser solutions to fully native ones.

Just start building with flutter, it's the best maintained platform that's the easiest to reason around. Everything follows a well defined workflow, you won't spend 30 days just learning the variety of configurations people keep for getting each different platform running.

If you go native you'll spend so much time deciding on platforms, build tools, packaging, etc.

It's better if you just start building and when you find deficiencies in Flutter you know what you search for in other platforms. You can move to them then.