i got a system that cannot boot and i have its SD card. I can see all the folders. Is there a way to see the installed packages, please?
On recent OpenWrt versions at least, info on installed packages are in /usr/lib/opkg/.
The list of all packages with some info on each is in text file /usr/lib/opkg/status.
Files with some more info on each installed package are in directory /usr/lib/opkg/info/.
Look there.
EDIT: All packages are listed including default packages and all the package dependencies. If you want just the list of packages to re-install or to add to the image-builder system, you need to figure all that out.
I worked on a shell script that runs on a linux host that does all that using the above mentioned files copied from the sd card or running OpenWrt system on my R4S. I'd have to look for it and test it if it is something you would like to try.