I'll give a vote of confidence for Flutter here. I've been using it as a one man show to develop a game ( markmywordsgame.com ) in the trickle of spare time I get. I use Firebase for back end.

Flutter is a dream to work with. Very rapid development with hot reload. Firebase is great for abstracting away almost all the dev ops bs. You can use local emulators for rapid development there too. It's quite a nice stack.

I happen to love Dart, and tolerate Typescript. I get to almost completely escape the js build hell, but Firebase functions do still require either JavaScript or Typescript.

I will include the caveat that Flutter web is not the best target for forms/text heavy projects. Flutter does all is own rendering so you don't get the html stuff like Ctrl f, copyable text, css "for free".

But for true apps that you don't just want to look like a word press site, it's awesome.