The things that are harder to get running in a browser via webassembly tend to have a GUI, network communication, or system calls that browsers don’t provide the APIs that are needed to support. But I’ve seen workarounds using websocket proxy servers to get around the lack of raw TCP or UDP socket access.
I’ve been surprised how easy it can be to get Python and C# code running in a browser.
I’ve been surprised how easy it can be to get Python and C# code running in a browser.