As a long time C programmer this is not very convincing. A C program to do the same requires far less voodoo. All you need to do is take the address of the GPIO register then toggle the bit. No name mangling. No error handlers to override. Don't get me wrong I know rust does have some compelling features. It does seem odd to me that so many of what would be compiler options in C are hard coded.
As the author said at the end, the general "good practice" for Rust is to encapsulate the weird stuff and unsafe blocks into a safe lib that other people can use.