I feel like if you were gonna overthink this, you could’ve done something really cute and clever.
Like an AI that stares at the window and figures out which angle the sun is coming in, then makes a determination on what time it must be.
Then while it’s not sunny or can’t figure it out, it has dead reckoning, but it’s constantly looking at angles of shadows that determine if the time has drifted.
It would just start counting