There is a book from newline.co called Fullstack Rust, which teaches actix as well as WebAssembly in rust.
One more thing: I’ve seen the creator Nikolay Kim and other core contributors of actix, fighting over the usage of unsafe. Nikolay was striving for the fastest thing possible, and others were striving for the safest one.
Nikolay Kim left the project and started another library/framework called ntex. Rest of the team replaced almost all the unsafe code with safe code. And the good thing is that actix is still as fast as ntex.