SD Disk Copying

I have installed OpenWRT on a Raspberry Pi 4B, and have a basic router working. I would like to add several more packages, NAS, an ad blocker, Apache and miniDLNA. Maybe others.

But first I would like to clone my working micro SD card so if I make a mistake I can recover easily. I am unable make a copy using Raspian's SD Card Copier.

Is there an easy, safe way to make a perfect copy of a working OpenWRT SD card?

You can copy the disk with dd utility in linux.
Or you could use the imagebuilder to prepare the image with the extra packages and settings.

Be aware that keys and possibly entropy will also be cloned which is probably not what you want...