I see, indeed. You’re using the board package as instructed from m5-docs, which is using the Arduino core https://m5stack.oss-cn-shenzhen.aliyuncs.com/resource/arduino/m5stack-2.0.3.zip. PlatformIO only supports the official Arduino-ESP32, which does not have the M5Stack-Paper (but other M5Stack boards), see here. Seems like the M5Stack people just fork the Arduino-ESP32 core, add their own boards, and don’t merge immediately back, leaving regular core users in the dark.
However, looking at the core download, it nicely has a package.json, so it can be used in PlatformIO, given the right board definition (already created in Create m5stack-paper.json by TomG736 · Pull Request #669 · platformio/platform-espressif32 · GitHub).
Could you try this example please? (Initial “Rebuilding Index” in VSCode might take long because it has to download the core from a slow chinese server…)