Game Mode fails to format microSD card on Konkr Pocket Fit

[stdevol]

Describe the bug
After installing the OS on the internal storage of Konkr Pocket Fit, formatting a microSD card from the Steam Game UI (Settings -> Storage -> Format SD Card) fails with an error.

To Reproduce

1. Install SteamOS-ARM-Handhelds onto internal storage.
2. Insert a microSD card (tested with a working card formatted on Steam Deck).
3. Go to Settings -> Storage in Game Mode.
4. Select "Format SD Card".
5. The formatting process fails with an error.