Trying to add support for the LongSung U9300C Modem

Hi all, a newbie here...

I have a ZBT-WE826/KuWFI router on hand and I had been messing around with it lately. I am trying to get the SIM modem functionality on it to work for some time now but nothing has worked out so far. The router uses a LongSung U9300C TD-LTE mPCIE Modem. I had read a few Chinese articles online on how to use the GobiNet driver to add support to the U9300C but I never get past the point of selecting the Kernel Modules for USB Support in make menuconfig as well as modifying the file option.c under the folder /drivers/usb/serial.

I had followed the instructions on the "Using the SDK" and I had ran the commands ./scripts/feeds update -a and ./scripts/feeds install -a, I also thought I had screwed up somewhere and I had started the process from scratch for the 3rd time now, but the result is still the same.

My question is similar to this article , I was not able to see the modules named kmod-usb-acm kmod-usb-core and etc.

So up to this point, my question is that how to I get the option.c file (like am I supposed to download it somewhere or what), and how to get all the kernel modules for USB (i.e kmod-usb-acm, kmod-usb-core) because I don't see them in make menuconfig?

Here are the 2 Chinese articles I tried to follow:
https://blog.csdn.net/IveLee/article/details/79030744
https://www.twblogs.net/a/5d1e166fbd9eee1e5c8356ad?lang=zh-cn

The version and platform of the SDK I am using is openwrt-sdk-22.03.2-ramips-mt7620_gcc-11.2.0_musl.Linux-x86_64

Thanks first!

Just another photo to illustrate what I am seeing
The only 2 modules I can currently see in Kernel Modules>USB Support are only these:

what does lsusb say about the modem ?

lsusb recognises the modem itself, listed as " Bus 001 Device 003: ID 1c9e:9b3c LONGSUNG USB Modem"
I will also attach a screenshot from cat /sys/kernel/debug/usb/devices

https://blog.cooky.tk/2019/09/05/long-shang-longsung-u9300-mo-kuai-linux-qu-dong/ would indicate you should use the option driver ?

Yea I know I need to use the option driver. But do I copy the one directly from here and just modify it according to the article and put it into the drivers folder?