It's not clear if we still need to install ESP-IDF.

[Jezza]

Both the esp book and this repository make no mention of requiring esp-idf, but it seems that the linker is still needed.

(It does look like it builds esp-idf, but in my current environment, it fails to build it.)

[MabezDev]

The esp-idf-sys crate build script downloads and compiles esp-idf.

By default it uses pio (platformio) to build esp-idf, however we now have a native feature of esp-idf-sys that uses cmake.