Got the same GPIO error msg...
Changing the ESP32 Espressif boards back to v 2.0.17 worked for my M5Stick C also. Never would have found that. Thanks greatly!

Just in case the linked document disappears, here's the gist:
Be sure the TinyGPS++ library is installed in
Arduino\libraries

TinyGPS++ here:
https://github.com/mikalhart/TinyGPSPlus/releases

// If your M5Stick is the original, use:
#include <M5StickC.h>　

// If its M5 Stick Plus 2 use:
#include "M5StickCPlus2.h" 

//The rest should be default:
#include "TinyGPS++.h"       
TinyGPSPlus gps;
HardwareSerial GPSRaw(2);     
void setup() {
  
  M5.begin(); 
 
  M5.Lcd.setRotation(3);
  M5.Lcd.fillScreen(BLACK);
  M5.Lcd.setTextSize(2);  // Size 1 or 2 as needed
  M5.Lcd.setCursor(20, 15);
  M5.Lcd.println("GPS UNIT TEST");
  GPSRaw.begin(9600, SERIAL_8N1, 33, 32); // M5StickC?GROVE???
  while (!GPSRaw) {
 ;                            // ???????????????
  }
} 
void loop() {
  while(GPSRaw.available()) {
    gps.encode(GPSRaw.read());
    if (gps.location.isUpdated()) {
      M5.Lcd.setCursor(20, 30);
      M5.Lcd.print("LAT="); M5.Lcd.print(gps.location.lat(),6);
      M5.Lcd.setCursor(20, 45);
      M5.Lcd.print("LNG="); M5.Lcd.print(gps.location.lng(),6);
      M5.Lcd.setCursor(20, 60);
      M5.Lcd.print("ALT="); M5.Lcd.print(gps.altitude.meters());
    }
  }
}

Got the same GPIO error msg...
Changing the ESP32 Espressif boards back to v 2.0.17 worked for my M5Stick C also. Never would have found that. Thanks greatly!