I don't have experience with external USB SSD's but they may behave the same, I had an external HDD myself
No, google drive is worse, store your stuff on your own physical devices, storage space is cheap enough these days.
Also, there's a very high chance you can buy another INTERNAL hard drive or SSD and put it into your computer. The process is VERY easy, you just have to open the case, slide the hard drive into one of the drive bays (or just leave it at the bottom of the case, but I don't recommend that), plug in the SATA Power, plug in the SATA, and close the case again.
EDIT: well, M.2 storage aren't connected by sata, so they are even easier, they literaly just plug into a slot and the you have a stand underneath their hole, and you screw them thru the hole
The hardest part of that is knowing what case panel you need to take off to access the drive bay lol, but you can just open the case panels randomly until you find it.
If the new drive doesn't show up in windows explorer right away, you may need to format it using a windows utility called "create and format hard disk partitions"