(Im new to this world) Creating custom image with make menuconfig etc

So im new to both linux and openwrt so its gonna be a long road i guess.

What im trying to do is follow this: https://openwrt.org/docs/guide-developer/quickstart-build-images
Then tried to look at this: https://openwrt.org/docs/guide-developer/packages

What i wanna do is make an image for my x86_64 hardware with stable 19.07.3 (or other if that doesnt work with what i want) and include a custom driver.
A driver that isnt included as an option in menuconfig, that is.
I think i have to create my own local package with my own local feed to install it? If it even works to do that? Like i said its gonna be a long road cause im new to linux aswell.
I really cant get the package to show in make menuconfig, im 99% doing it wrong.

This is the driver: https://www.realtek.com/en/component/zoo/category/network-interface-controllers-10-100-1000m-gigabit-ethernet-usb-3-0-software

I got 2.5Gbit usb->ethernet adapter i want working and kmod-usb-net-rtl8152 doesnt seem to do the trick

Anyone wanna point me in the right direction or know of a good guide for noobs?

EDIT: Or maybe that kmod is that driver im not sure