this is the file I'm trying to flash via uboot as in the instructions per wiki:
https://downloads.openwrt.org/releases/23.05.4/targets/ath79/generic/openwrt-23.05.4-ath79-generic-glinet_gl-ar300m16-initramfs-kernel.bin
I'm getting this error:
What's running on that device currently? Is your unit 16M?
If you already have OpenWrt on there, you should be able to use the sysupgrade image and upgrade directly from the web UI when the router is fully booted.
You are using the wrong image.
Even for uboot, on this device, use the sysupgrade image.
(The clue is in the uboot error - wrong image)