if you are already expert on technologies you mentioned and know exactly how to work with them you might see investition to flutter as burden. Otherwise: Just go on with flutter & flame and see if it fullfills your requirements and could fit to your exact requirements.

Generally, flutter is already solid, and usable in context you mentioned. There's also plenty of resources to test if it would be ok to you before investing a lot. Just pick a demo project, get it running, and see results.

https://flutter.dev/games

If you decide to invest you can take a working seed project generated to you

https://cli.vgv.dev/docs/templates/flame_game

Note: Flutter + Flame expect you to learn dart - it's easy, as the language is close to js / c / .. so: algol style syntax - it also expects you to understand reactive ui's - well: concept is insipired by React, so no suprises here, except that the whole concept needs some discipline.

Still to mention: For 3d games you still should see unity as solid option. And, as also with react native, you would find integration to flutter possible and supported by 3rd parties. Don't expect this to work always out of the box as a dream, but see it as a doable thing if you need to step to this road.

https://pub.dev/packages/flutter_unity_widget

As an inspiration I give you idea what kind of extensions Flutter offers, if you decide to invest on it.. This is more fun thing, but as a junior developer learning stuff and doing things out of interest this might be something to you.

https://www.youtube.com/watch?v=0CCVB31feO0

I think you should stick with the thing you know because flutter is a whole new ecosystem and you could shoot yourself in the foot with it and when you have made the app then you could learn flutter