Can't get ESP32C6 to work in PlatformIO. Error is "unsupported ISA substring '_zicsr_zifencei'"

Question

I bought a few Waveshare ESP32C6 Touch LCD 1.47 boards and have had a hell of a time trying to get my sketch uploaded. I somewhat understand that PIO doesn't support esp32c6 because:

The ESP32 Core for Arduino 2.x is the most recent major version currently recommended for use with PlatformIO. The decision to discontinue support was made by the Espressif company, as indicated in their official statement: espressif/arduino-esp32#8606 - https://github.com/platformio/platform-espressif32/issues/1225

However, I've seen a number of post where people claim to have gotten it working.

I finally got rid of the errors when saving the platformio.ini file, but this is the final boss for me.

Here's the error that I'm getting.

Compile errors

...
Building in release mode
Compiling .pio/build/waveshare_esp32c6_touch_lcd/src/main.cpp.o
Building .pio/build/waveshare_esp32c6_touch_lcd/bootloader.bin
Generating partitions .pio/build/waveshare_esp32c6_touch_lcd/partitions.bin
esptool.py v4.5.1
Creating esp32c6 image...
Merged 2 ELF sections
Successfully created esp32c6 image.
Compiling .pio/build/waveshare_esp32c6_touch_lcd/libf61/SPI/SPI.cpp.o
cc1plus: error: -march=rv32imac_zicsr_zifencei: unsupported ISA substring '_zicsr_zifencei'
cc1plus: warning: unrecognized command line option '-Wno-enum-conversion'
Compiling .pio/build/waveshare_esp32c6_touch_lcd/libe72/FS/FS.cpp.o
*** [.pio/build/waveshare_esp32c6_touch_lcd/src/main.cpp.o] Error 1
cc1plus: error: -march=rv32imac_zicsr_zifencei: unsupported ISA substring '_zicsr_zifencei'
cc1plus: warning: unrecognized command line option '-Wno-enum-conversion'
*** [.pio/build/waveshare_esp32c6_touch_lcd/libf61/SPI/SPI.cpp.o] Error 1
cc1plus: error: -march=rv32imac_zicsr_zifencei: unsupported ISA substring '_zicsr_zifencei'
cc1plus: warning: unrecognized command line option '-Wno-enum-conversion'
*** [.pio/build/waveshare_esp32c6_touch_lcd/libe72/FS/FS.cpp.o] Error 1

platform.io

...
[env:waveshare_esp32c6_touch_lcd]
platform = espressif32@~6.8.0
platform_packages = 
 framework-arduinoespressif32 @ https://github.com/espressif/arduino-esp32/releases/download/3.0.1/esp32-3.0.1.zip
 framework-arduinoespressif32-libs @ https://github.com/espressif/arduino-esp32/releases/download/3.0.1/esp32-arduino-libs-3.0.1.zip
board = waveshare_esp32c6_touch_lcd
framework = arduino
monitor_speed = 115200
lib_deps = 
 lvgl/lvgl@^9.1.0
 bodmer/TFT_eSPI@^2.5.43
build_unflags = -std=gnu++2b
build_flags = 
 -D LV_CONF_INCLUDE_SIMPLE
 -D LV_LVGL_H_INCLUDE_SIMPLE
 -I ../lib/ui
 -I ../include
 -D CORE_DEBUG_LEVEL=5
 -std=gnu++2a
board_build.arduino.stack_size = 16384

waveshare_esp32c6_touch_lcd.json

{
 "build": {
 "arduino": {
 "ldscript": "esp32c6_out.ld",
 "partitions": "default.csv"
 },
 "core": "esp32",
 "extra_flags": [
 "-DARDUINO_ESP32C6_DEV",
 "-DARDUINO_USB_CDC_ON_BOOT=1"
 ],
 "f_cpu": "160000000L",
 "f_flash": "80000000L",
 "flash_mode": "qio",
 "hwids": [
 [
 "0x303A",
 "0x1001"
 ]
 ],
 "mcu": "esp32c6",
 "variant": "esp32c6"
 },
 "connectivity": [
 "bluetooth",
 "wifi"
 ],
 "debug": {
 "default_tool": "esp-builtin",
 "onboard_tools": [
 "esp-builtin"
 ],
 "openocd_target": "esp32c6.cfg"
 },
 "frameworks": [
 "arduino",
 "espidf"
 ],
 "name": "Waveshare ESP32-C6-Touch-LCD-1.47",
 "upload": {
 "flash_size": "4MB",
 "maximum_ram_size": 327680,
 "maximum_size": 4194304,
 "require_upload_port": true,
 "speed": 921600
 },
 "url": "https://www.waveshare.com/wiki/ESP32-C6-Touch-LCD-1.47",
 "vendor": "Waveshare"
}

What should I try next? It sounds like it comes down to versions at this point.