With these things in mind, we looked at how we could keep the good ideas from Draft, Slate, ProseMirror and also invent some new ideas of our own. Lexical doesn't have any dependencies, so you can use it with Svelte or Solid (once their bindings have been created), or any other framework of your choice. Lexical also doesn't need ImmutableJS, which means the APIs are fully typed in Flow and TypeScript, reducing issues. Lexical is also around 22kb gzip+min, so it's far smaller than Draft. Typing performance in our testing is around 30-70% faster compared to Draft.
I'd recommend checking out the playground and its sourcecode and seeing what you can build yourself with Lexical. We really think we're on to something here :)