STM32F7x6 - Setting readout protection from code without power cycle

Question

I am working on a custom battery powered board with a STM32F746 on which I would like to set the RDP option byte to level 1 from code. Basically, while booting the software checks if the option bytes are set correctly and if not it will reprogram the option bytes to the correct values. This means that any unit shipped to customers is ensured to have the read-out protection set and we don't have to worry about the assembly house forgetting to set it and thus exposing the firmware.

To do this, I follow the procedure in the reference manual:

1. unlock the option bytes by writing the correct keys to FLASH_OPTKEYR and clearing OPTLOCK
2. set the desired option values in FLASH_OPTCR
3. set OPTSTRT in FLASH_OPTCR

This works fine for all option bytes except RDP, which locks the MCU after setting OPTSTRT. As far as I can tell, this is intended behaviour, and requires a reset of the device through a power cycle after which the option byte is set correctly. But since our board is battery powered (soldered connection) this is a bit cumbersome and so my first question is if there exists another way of doing this.

A bit of googling revealed that some STMs can also activate the altered option bytes by transitioning from the STBY state, here is a specific example by ST: https://www.youtube.com/watch?v=f7vs0NwZPFo&ab_channel=STMicroelectronics. So far I have no luck with this method: when returning from STBY the RDP is not set. The example deals with an STM32L4, does anyone know if this method is supported on the F7?