Very sorry to hear about your issues with Surface Go. The Surface Go 2, has its storage soldered in the motherboard, which means it not designed for user-replaceable storage.Hereare a detailed explanation of your options:
>Since the storage is not user-replaceable, the safest and most reliable option is to have a professional service handle the replacement. This involves desoldering the existing eMMC storage and soldering a new one, which requires specialized equipment and expertise.
> Attempting this by own is highly risky due to the precision required in desoldering and soldering micro components. I wont recommned it.
>Best solution is to use External Storage like MicroSD Card as Surface Go 2 has a microSD card slot. You can use high-capacity microSD cards (up to 1TB), Use USB-C or USB-A storage devices for additional space ot use and external hard disk attachment wit USB.
If you need further assistance or if any of these steps are unclear, please let me know.