This is not fail as such, but I believe it is good lesson learned and also trick to have in a sleeve, so I will publish it here (maybe just for future myself being lost again).

When connecting MCU to PC via USB, it is quite useful to fit external pull-up resistor in series with MCU controlled PFET to 3.3V supply. This allows you to turn the pull-up off and on during MCU boot and inform USB hub to re-enumerate your device without re-inserting the connector (for instance during debugging sessions).

A USB device must indicate its speed by pulling either the D+ or D- line high to 3.3 volts. A full speed device, pictured below will use a pull up resistor attached to D+ to specify itself as a full speed device. These pull up resistors at the device end will also be used by the host or hub to detect the presence of a device connected to its port. Without a pull up resistor, USB assumes there is nothing connected to the bus. Some devices have this resistor built into its silicon, which can be turned on and off under firmware control, others require an external resistor.
https://www.beyondlogic.org/usbnutshell/usb2.shtml

Im typically doing it like this:Well few days ago, while reusing one of my very old and obsolete PCB without external switchable pull-up, I had to write new firmware and each debug session start I had to re-insert the connector, which was mind numbing and after some time I started to look for software workaround. Im not sure whether this is USB compliant hack, but it certainly works.
Before initializing USB peripheral in MCU, D+ pin (USBP) is configured as GPIO output push-pull and set low (0V) for 5ms. After that standard USB configuration including GPIO is performed. After this procedure USB host recognizes new device and starts enumeration.

/*******************************************************************************
                       LL Driver Callbacks (PCD -> USB Device Library)
*******************************************************************************/
/* MSP Init */

void HAL_PCD_MspInit(PCD_HandleTypeDef* pcdHandle)
{
  GPIO_InitTypeDef GPIO_InitStruct;
  if(pcdHandle->Instance==USB)
  {
  /* USER CODE BEGIN USB_MspInit 0 */

    GPIO_InitStruct.Pin = GPIO_PIN_12;
    GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
    HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
    HAL_GPIO_WritePin(GPIOA, GPIO_PIN_12, GPIO_PIN_RESET);
    HAL_Delay(5);

  /* USER CODE END USB_MspInit 0 */
  
    /**USB GPIO Configuration    
    PA11     ------> USB_DM
    PA12     ------> USB_DP 
    */
    GPIO_InitStruct.Pin = GPIO_PIN_11|GPIO_PIN_12;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
    GPIO_InitStruct.Alternate = GPIO_AF14_USB;
    HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

    /* Peripheral clock enable */
    __HAL_RCC_USB_CLK_ENABLE();

    /* Peripheral interrupt init */
    HAL_NVIC_SetPriority(USB_LP_IRQn, 5, 0);
    HAL_NVIC_EnableIRQ(USB_LP_IRQn);
  /* USER CODE BEGIN USB_MspInit 1 */

  /* USER CODE END USB_MspInit 1 */
  }
}

 I hope this helps someone in the future. Im wondering whether this is fully compliant routine to re-enumerate USB device and Im using external pull-up and PFET all the time redundantly? Please comment if you know the answer :)