Creating a new PlatformIO platform is a very involved task. It needs a lot of background knowledge on how PlatformIO works internally (platforms, packages, frameworks, board definitions, builder scripts) as well as how microcontroller firmwares are created in general (compiler options, linker scripts, startup assembly files, upload programs like OpenOCD, debugger probes, …).
A good point to start reading would be
- https://community.platformio.org/t/arduino-due-or-other-sam3-4-upload-fails-with-atmel-ice-jtag-on-vscode-with-platformio/22258/8?u=maxgerhardt
- https://docs.platformio.org/en/latest/platforms/creating_platform.html#platform-creating
- https://docs.platformio.org/en/latest/platforms/creating_board.html
- https://interrupt.memfault.com/blog/zero-to-main-1
- https://interrupt.memfault.com/blog/how-to-write-linker-scripts-for-firmware
- https://gcc.gnu.org/onlinedocs/gcc/ARM-Options.html etc.
Also know that someone already created a PlatformIO platform for PY32F0 chips:
Adding a new board definition, updating or adding new framework packages and modifying the builder scripts to work for those chips will be easier than creating a new platform from scratch. But for that, you would have to at least read through all previous links to get started.