@gabrielapb You could try the following:
save the current timestamp to NVS before going to sleep
on wake-up:
retrieve the saved timestamp from NVS
retrieve the "remaining sleep" from the Pysense using pysense.get_sleep_remaining
current timestamp is approximately saved + sleep interval - remaining
Note this won't get you a very precise time (as it doesn't take into account boot time, and I'm not sure of the accuracy of the Pysense clock), and the offset to the real time will increase with the number of sleep periods, but it's helpful to have at least of rough idea of the time until you can get the actual time through other means.
The alternative is to use the module's deep sleep rather than the Pysense's deep sleep, but that may not be possible depending on your actual use case.