Your system information

• Steam client version: 1733265492
• Distribution: CachyOS Handheld
• Opted into Steam client beta?: Yes, Steam Deck Beta
• Have you checked for system updates?: Yes
• Steam Logs: steam-logs.tar.gz
• GPU: AMD

Please describe your issue in as much detail as possible:

Here is the current Vietnamese keyboard:

How does this even happen?

Most, if not all Vietnamese people use keyboards with ANSI/ISO layout and use the Telex input method to type Vietnamese characters.
I think it is better to design a keyboard that Vietnamese people already familiar with instead of that monstrous layout.

Steps for reproducing this issue:

1. Launch Steam in Big Picture mode.
2. Settings > Keyboard > Active Keyboards > Edit.
3. Enable the Vietnamese layout.
4. Trigger the keyboard by going to the top left search bar.

These might be helpful:
https://github.com/fcitx/fcitx5-unikey
https://github.com/fcitx/fcitx5-bamboo