Expand root partition about openwrt-nanopi-r2s-r4s-builds

[anaelorlinski]

I cannot guarantee it works but I would say expanding ext4 is pretty common task. I would recommend to backup the card in any case if you already have a complex setup. That's the power of those devices you can switch SD cards easily.

You need first to expand the partition size and then can expand the filesystem.
https://openwrt.org/docs/guide-user/installation/openwrt_x86#resizing_filesystem

For ext4 you can either follow the procedure or do it offline on a desktop system with a GUI utility.
For squashfs it is more complicated to do it offline but I integrated all the tools in the image to do it, and you can find the instructions in https://github.com/anaelorlinski/OpenWrt-NanoPi-R2S-R4S-Builds/blob/main/docs/resize-f2fs.md