GL.iNet GL-MT300N-V2 - Reading serial number

I'm currently building a custom image for a GL.iNet GL-MT300N-V2. I was looking for a way to get the device's serial number and after poking around I found it in /dev/mtdblock2 (@ 0x4030). I was planning to write a really simple C application to retrieve it (because I have a use case where I need it) but I was wondering if this something that could be useful to someone else. And if that is the case what would be the best way to provide it ? Patching cpuinfo ? Something else ? Thanks in advance for your comments.

Why serial no?

we normally use device MAC address.

Hmm... good point. Maybe because in my mind the serial number was more "reliable" than the MAC address to identify a device. I've read the QR code that is on the back of the case and it returns the serial number, the custom DDNS, and the MAC address. So maybe you're right and I should stick to the MAC address instead of the S/N.