It's more than just an idea, it's a good idea. They already have it in the M5 Unified library, they just need to backport it to Core2. I filed a pull request. I hope they accept it:
https://github.com/m5stack/M5Core2/pull/138
I thought that you could use the RTC::ReadReg method directly to read the bit, something like return Rtc.ReadReg(0x02) & 0x80;, but unfortunately the method is private.
Hope this helps
--Louis