Firmware update for Gokod X9

I recently bought a 4G Portable router pre-installed with OpenWRT and LuCI interface. However, the firmware is version 1.8 and I couldn't find the brand's website for online support. OpenWRT also didn't list the brand or the model in the list it supported. I'm calling if anybody has clue how to update the firmware. I'm not familiar with linux and not an IT guy so I'm not capable of building the firmware myself. If anybody can help build me the firmware update, here is the specification:
Brand: Gokod
Type: Smart Router
Model: X9
Color: White
Transmission rate: 300Mbps
Main CPU: MT7628
Memory: DDR2 64MB
Flash: SPI 8MB
Protocol: IEEE 802.11b/802.11g/802.11n/802.3/802.3u
Frequency: 2.4GHz
Antenna: 2 3dB 2.4G 2R2 internal antenna
5dB 4G 2R2 internal antenna
Port: 1
Sim card port,1
Wan,1 TF
LED: Charger,Power,2.4G wireless,4G network
Button: 1
Reset button,1*Power button
Max power consumption:<10W
Scope of application: Family routing

Is it possible for me to upgrade using an image from a different brand that has similar specification?. I saw that Duzun DM06,, has a similar specification to Gokod X9.

If it isn't listed in the table of hardware , it isn't supported. Routers are embedded devices, usually with quite come quirks and peculiarities, and little standard adherence (so those exist in the first place), so each device needs its very own bespoke firmware image - there usually are no generic images. Just shoving an image for a remotely similar device is pretty much guaranteed to brick it, quite probably without any way to recover.

That doesn't mean it's impossible to add support for it, but someone (this could be you) with the device on their desk still needs to actually do the hard work of porting it to OpenWrt and submitting the resulting patches for merging into OpenWrt. But if you have to ask about this, you probably won't be able to accomplish it.