No you cannot upgrade or replace the memory since it is integrated into the Logic Board. The 2017 MBPro non-touchbar model does have a removable SSD, but it is yet another unique proprietary Apple PCIe SSD connector. AFAIK, there are no third party drop in replacement SSDs for this laptop, although you may find used Apple SSDs online at vendors like Beetstech:
https://beetstech.com/product/macbook-pro-13-inch-a1708-ssd-replacement-kit
While I've seen posts that people have installed a third party SSD into this laptop using an adapter each of those posts were reporting issues with the third party SSD so I would not recommend this option since the third party SSD manufacturer will not provide support on this laptop since you would be using an adapter.
You can use an external USB3 drive for extra storage. Just make sure to backup the external drive in addition to your laptop so you minimize the risk of losing your precious data in case of an accident or a hardware failure.
In the future be very careful to purchase a computer with enough memory and storage since none of the Apple laptops allow for upgrades after purchase. Even some non-Apple computers limit upgrade options after purchase.