I also bought this one because I wanted a passive solution. Temperature looks fine (45°C in Idle). Although I think there are different versions and some of them don't fit perfectly on the RPi4. I got mine from amazon and it cools the three most important chips but the position where it touches the chips isn't perfect.
What one should mention is that his version of coroutines is also stateless. That's why you need either stackful coroutines written in assembly or support in the language/compiler or operating system. Special case versions where you can avoid backing up the stack frame exist in other projects too, like in asio: https://github.com/chriskohlhoff/asio/blob/master/asio/inclu...
But in my opinion I would not use them for generic use cases and rather wait for the official support in C++20.
Of course I'm aware that I'm talking about C++ here and the situation for C might be slightly different.
