If it works, I think it's a really good idea. I've been using VS Code for almost everything except Jupyter... but still a bit. VHDL, Python, you name it, it goes through VS code. The Quartus editor is so bad, it's better to work on VS Code and just click on the "compile" button.
Back on topic, I briefly tried PIO on Windows, and I found it difficult to just get a microcontroller (STM32L4 I think, with custom hardware) up and running. Lots of dev kits though. But I didn't immediately dislike it, just didn't look into it enough.
I believe CubeMX does generate a Makefile project if necessary. Just add your own sauce I guess... but I never tried.
Cheers,
Alberto