Install YAY on steam deck commands

steam_deck_install_yay.sh

# Allow to write over file system (steam os block)
sudo steamos-readonly disable

# Ensure we have the keys updated
sudo pacman-key --init
sudo pacman-key --populate archlinux
sudo pacman-key --populate holo
sudo pacman -S glibc linux-api-headers

# Install git and base-devel dependencies
sudo pacman -S --needed git base-devel
# Ensure that dependencies get installed correctly (this may be not necessary in some cases)
sudo pacman -S git base-devel
# When prompted, select all options

# INSTALL FROM SOURCE
git clone https://aur.archlinux.org/yay.git
cd yay
git checkout 17f4503492f5070ebcca58743144773c89099dff # version 12.3.1 (last before pacman 6.1 requirement)
makepkg -si

# OR INSTALL FROM BINARY
# git clone https://aur.archlinux.org/yay-bin.git
# cd yay-bin
# makepkg -si


# Disable again the write over file system
sudo steamos-readonly disable

@deckOuser it looks like it could be related to pacman. Try running this to see if it solves: sudo pacman -S pacman (https://www.reddit.com/r/SteamDeck/comments/12cwir4/yay_installation_fatal_error_alpmh_not_found/)