Hello @bugsounet,
Your question gave me a clue on what to investigate. Turns out, adding the user to “dialout” group in ubuntu is essentially same as “gpio” in raspberry pi os. I ran these commands:
sudo apt install rpi.gpio-common
sudo adduser "${USER}" dialout
sudo reboot
and all worked well. Timer works, screen shuts off as expected, turns on as expected. Maybe this is what I get for being the 1% of people doing this via ubuntu on a pi!