Pre-made compressed Debian Bullseye chroot images, generated with Github Actions
Tested on Openwrt 19+
wget download link
gunzip -c downloadedfile bullseye.img
mkdir /mnt/bullseye
mount bullseye.img /mnt/bullseye/
mount --bind /dev /mnt/bullseye/dev/
mount --bind /proc /mnt/bullseye/proc/
mount --bind /sys /mnt/bullseye/sys
cp /etc/resolv.conf /mnt/bullseye/etc/resolv.conf
chroot /mnt/bullseye
To run Debian apps on start, simply install & use screen after chroot command in rc.local/rc.d/init.d service...