The SanDisk microSD Express Card is not specifically designed for the Raspberry Pi 3 B+. The Raspberry Pi 3 B+ usually supports microSD cards with UHS-I, and the microSD Express cards use a different interface that is not fully compatible. Therefore, there may be compatibility issues. It is advisable to use a UHS-I microSD card that is specifically recommended for the Raspberry Pi, such as the SanDisk Extreme Pro.

Works, but what exactly is the point? The Switch only has a limited read and write speed...