Expanding OpenWrt squashfs image (SDcard)

Here's what worked for me on OpenWRT 22.03.2 with SquashFS.

1. Flash image to SD as normal with the firmware selector (I added packages to mine)
2. ssh into router
3. "opkg update && opkg install cfdisk resize2fs"
4. "cfdisk /dev/mmcblk0"
5. Create a NEW PRIMARY partition in the free space at the end. Delete this new partition. Select /dev/mmcblk0p2 and RESIZE it. The default entries will take the whole space.
6. Reboot
7. ssh into router
8. "resize2fs /dev/loop0"
9. Success!