Yes, with advanced scripting you can execute arbitrary code and inject new targets / files in src/ in the build system (which is the Python-based SCons system). An example of that can be found for ESP32 ULP (ultra-low-power processor) assembly files: platform-espressif32/ulp.py at develop · platformio/platform-espressif32 · GitHub, or Problem when compiling ESP32 ULP sources (framework Arduino) · Issue #315 · platformio/platform-espressif32 · GitHub.
A good understanding of PlatformIO + SCons is however required for this. You may find some initial guidance here.