In STM32G030x6/x8 datasheet (DS12991 Rev 3, Table 12 on page 31) I see only input pin for external HSE clock source (LQFP32, pin 2 - PC14 - OSC_IN), but don't see OSC_OUT pin of HSE OSC.
Thanks for your reply. It is a pity, that the documentation does not explicitly state that the HS OSC of the STM32G030 MCUs in the TSSOP20 and LQFP32 packages can only work from an external clock generator.