When I compare their platforms.local.txt against Arduino-ESP32’s, the main addition just seems to be
The addition of 3 defines in the build process. As shown in the docs, you can get the exact same behavior when you write
build_flags = -DDONT_USE_UPLOADTOBLOB -DUSE_BALTIMORE_CERT -DUSE_MBEDTLS
in the platformio.ini.
Notice that per their documentation, you might want / need different certs