Can I upgrade the SSD in a 2017 MacBook Pro 13-inch Touch Bar?

Regarding the MacBook Pro: It depends on the configuration — some have the SSD soldered to the board, making upgrades impossible. Others use a proprietary Apple connector (not standard M.2), but you can replace them with a compatible third-party drive or an adapter-based M.2 NVMe. The interface is PCIe 3.0 x4 NVMe, so performance is solid, but the process is unnecessarily complicated.