mbedcrypto | a portable , small , easy to use and fast c14 library

Get a release rather than a snapshot of the development branch.

Alternatively, in the 3.0+ development branch, according to the readme:

The source code of Mbed TLS includes some files that are automatically generated by scripts and whose content depends only on the Mbed TLS source, not on the platform or on the library configuration. These files are not included in the development branch of Mbed TLS, but the generated files are included in official releases. (…)

Before running cmake,

On Windows, run scripts\make_generated_files.bat to generate all the configuration-independent files.

This requires perl, python and a C compiler. You may need to set the CC environment variable to the path to cl.exe from Visual Studio.

The ESP-IDF build system is built on top of CMake. This means you can use all the standard features of CMake in your files. However, the the ESP-IDF system predefines many functions, and makes many assumptions about the layout of your project, supposedly to make things "easier". Instead of reading CMake documentation, start by reading and understanding the ESP-IDF build system documentation:

https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-guides/build-system.html

It looks to me like there is a particular layout expected for subcomponents, including the format of the CMakeLists.txt file. Specifically, move Metriful under a new directory called components, or add Metriful to EXTRA_COMPONENT_DIRS near the top of your root CMakeLists.txt

If Metriful is not written as an esp-idf component, this may not work. However, the document also describes how to link to "pure CMake" components, which will look something like this (at the end of your root CMakeLists.txt).