iced really need better documentation. I try to get into it and have a hard time.

It’s common rule in many communities, not just in Lemmy. Some are more strict, some are less, some are completely free in that regard. It’s a good habit to look if the post or topic was created already. If so, there is usually no need to do another and split all discussions, if it does not provide anything new. Also moderation would become almost impossible. It’s better to put same topic into one place. Also to avoid repetition, answering same question repeatedly, showing lack of research and the resulting overwhelming information density (which is a moderation problem).

I wish Rust would adopt tokio (or any other, if better suited) as a default first citizen async runtime. Then everyone can be sure to write in that runtime , knowingly it will run. If people need a different runtime, they could still opt out of tokio and opt in to whatever they like. The freedom of choice would not be hindered, but we would gain a default runtime.

What’s stopping this from happening?

Do you mean compiler running on the Watch? Because the compiled code is no longer Rust and therefore there is no reason why it should not run on the Watch. Or do you mean specifically applications with the Rust library Egui?