I recently updated from Firmware 1.6 to the 1.7.9.6 "ROGUE" firmware as linked to by the official RGHandhelds web site.
After doing so, my ext2-formatted external microsd card no longer gets automounted to /media/sdcard like it did under Firmware 1.6. And there appears to be no fstab entry for it on the read-only system volume that would cause it to automount, either -- and because the volume containing /etc/fstab is read only, I can't add one!
To mount the external sdcard, I have to physically connect the RG350 to my PC using the USB-C cable, ssh into it, and then run mount /dev/disk/by-label/sdcard /media/sdcard to get it to mount, which is extremely non-ideal.
Why doesn't the external microsd automatically get mounted anymore? Obviously the ext2 filesystem is still supported, because it mounts just fine manually.