I'm trying to initially flash OpenWRT ( open source) on Gl.inet Beryl MT-1300 and I'm getting a strange error message (see screenshot below). I installed Luci via Advanced and opend the luci webinterface, tried the firmware upgrade. It states that the uploaded OpenWRT image is not supported.
I tried 23.05.0 and 22.03.0, both the same message.
Should I force the flash and everything will be fine? I don't want to brick my router...
It should not brick. You will have to redo some of the network configuration in DSA format. You may want to export your existing configuration to a file so you can read it for reference. Definitely never try to copy config files directly from the GL installation to official OpenWrt.