It’s strange, I get around 170µA using a sketch based on the one above (supplier says 300µA in deep sleep).
LowPower library is working fine. Using internal watchdog add around 5µA consumption.
Having an external RTC will give you much more accurate timing.
Moreover, on LoRa32u4 there’s an internal “VBat/2” bridge divider plugged on ADC12 (D9).
In the end, LoRa32u4 is still a “big” development board, your 60µA ESP32 board is a nice and more compact alternative.