[ZOTAC Zone] Battery time remaining and charging time are missing

Your system information

• Device: ZOTAC Gaming ZONE
• Steam client version: 1789606022
• SteamOS version: 3.9.1 OS build: 20260914.100
• Opted into Steam client beta?: Yes
• Opted into SteamOS beta?: Yes, Preview
• Have you checked for updates in Settings > System?: Yes

Please describe your issue in as much detail as possible:

In Gaming Mode on the ZOTAC Gaming ZONE:

• While discharging, the remaining battery time always shows 0h 0m.
• While charging, it says Calculating charging time and then becomes blank.

Both estimates work correctly in KDE Desktop Mode.

The battery provides energy_now, energy_full, and power_now, but not voltage_min_design. This may be related to how vpower handles the available battery data, since UPower calculates both estimates correctly.

I created and tested a userspace workaround that reads the estimates from UPower and makes them available to Gaming Mode. It restores both remaining battery time and charging time on my device. The implementation is available here in case it is helpful for investigating the issue:

https://github.com/DeckFilter/DeckyZone/blob/101106595640be125f418b2dc5624067c6a713e7/py_modules/remaining_battery_time.py

Steps for reproducing this issue:

1. Open the Quick Access Menu in Gaming Mode on a ZOTAC Gaming ZONE.
2. While discharging, the estimate shows 0h 0m.
3. Connect the charger. It says Calculating charging time and then becomes blank.

Start by reading the linked py_modules/remaining_battery_time.py workaround and compare its UPower estimates with the Gaming Mode behavior described for vpower. Reproduce the issue on a ZOTAC Gaming ZONE in Gaming Mode while discharging and charging; done means both remaining and charging time estimates display correctly.