Can I power the just the esp32 RTC using a coin cell?

[Nachiketlog9]

My aim is to keep time even during power down of my device and I want to know if I can just keep the power to the internal RTC in esp32 using a coin cell, without keeping any of the other parts of esp32 ON or even in ULP modes. I see in the datasheet that the current required for VDD3P3_RTC is around 40 mA and typical duracell coin CR2032 proviedes about 0.4 mA continuously. However VD3P3_RTC does also provide power to few other peripherals. Am I just better of using an external RTC with a coin cell?
If any of you guys have solved this sort of problem what did you do? Thanks!