ESPHome builds ESP8266 firmware without Rosetta on Apple Silicon

ESPHome changes the default build system for ESP8266 devices, using its own packaged compiler and Arduino framework instead of fetching them from the PlatformIO registry. Apple Silicon Macs run the compiler directly without Rosetta, and Device Builder gains a compilation percentage for these devices.

J. Nick Koston measured a fresh build without a compilation cache at 9.2 seconds instead of 17.8 on an M5 Max, using a configuration with networking, a web server, a sensor and a light. Tests of the compiler and framework packages produced firmware identical to the previous packages.

The first build after switching starts clean. Configurations using a custom framework source, a version other than 3.1.2 or an unlisted board must explicitly keep toolchain: platformio for now. Hosts outside the supported Linux, macOS and Windows builds also need an alternative. The PlatformIO route is deprecated for removal in 2027.4.0, when configurations still requiring it will stop building.