So I made some tests on Esp32-C6 and Sim7080g connectivity. I used Sim7080g Waveshare Raspberry Pi Pico Shield. Everything works well, but the connections are not very trivial:

• ESP32_C6_GPIO_BUG_20->Waveshare_SIM7080G_PWR
• ESP32_C6_GPIO_BUG_23->Waveshare_SIM7080G_DTR
• ESP32_C6_BUG_GPIO_19->Waveshare_SIM7080G_RXD
• ESP32_C6_BUG_GPIO_18->Waveshare_SIM7080G_TXD
• ESP32_C6_BUG_5V->Waveshare_SIM7080G_VBUS
• ESP32_C6_BUG_3.3V->Waveshare_SIM7080G_VSYS
• ESP32_C6_BUG_3.3V->Waveshare_SIM7080G_3V3
• ESP32_C6_BUG_GND->Waveshare_SIM7080G_GND

When testing GPS example, it's necessary to put the GPS antenna outside!

The examples are available from the github repo.