I have had the same mindset as you. I got a project to create a website including the backend. At that time I started learning Flutter and Flutter Web also got released. But Flutter is easier to learn and faster to develop when comparing to other frameworks like React Native and all. Since I am familiar with Java and C# Dart was easy for me to learn. So I started to develop the website in Flutter Web. I finished most of the things within two weeks including the backend. But there is a problem in the performance when scrolling. It's a known issue. Same happening when browsing the site in the mobile browser. So I had to change the Framework from Flutter to Angular Dart. I started learning Angular TS few years ago by watching Udemy tutorials. But unfortunately I did not understand anything. But I learned Angular Dart myself by looking at the Documentation. Now I am good with the Angular Dart. As you have said in the post, code sharing will be a problem but only the code that you could share is Business Logic. You have to re create the UI for each Framework. It's not a big deal.