webthing-cpp is header-only and can be used from CMake via:

  find_path(WEBTHING_CPP_INCLUDE_DIRS "bw/webthing/webthing.hpp")
  target_include_directories(main PRIVATE ${WEBTHING_CPP_INCLUDE_DIRS})

However it requires

  find_package(nlohmann_json_schema_validator CONFIG REQUIRED)
  target_link_libraries(main PRIVATE nlohmann_json_schema_validator::validator)

  find_package(unofficial-uwebsockets CONFIG REQUIRED)
  target_link_libraries(main PRIVATE unofficial::uwebsockets::uwebsockets)