firmware/variants/portduino-buildroot/platformio.ini

[env:buildroot]
extends = portduino_base
; The pkg-config commands below optionally add link flags.
; the || : is just a "or run the null command" to avoid returning an error code
build_flags = ${portduino_base.build_flags} -O0 -I variants/portduino-buildroot
  -std=c++17
  !pkg-config --libs libulfius --silence-errors || :
  !pkg-config --libs openssl --silence-errors || :
board = buildroot
lib_deps = ${portduino_base.lib_deps}
build_src_filter = ${portduino_base.build_src_filter}