Hi Trevor,
You could plug an RTC into the exposed headers easily enough, but it’s a little messy.
To have an internal solution you might be able to fit this QWIIC shim (SparkFun Qwiic SHIM for Raspberry Pi | DEV-15794 | Core Electronics Australia) in the case and use a QWIIC compatible RTC (Adafruit PCF8523 Real Time Clock Breakout Board - STEMMA QT / Qwiic | ADA5189 | Core Electronics Australia) and a cable (PiicoDev Cable 100mm | Core Electronics Australia). It’d all be solder free. Teh QWIIC shim is just I2C so you could probably connect any I2C RTC to it.
