Netac ZX20 External Portable NVMe SSD, USB 3.2-C, 2000MB/s Read/Dust-Resistant 512GB £50.99 1TB £81.59 @ Amazon/ Netac Official Store

A USB-C connector has two extra serial channels in addition to the standard USB 2.0 channels. Each channel is capable of supporting up to 5Gb/s (realisically equivalent to between 340-450MB/s). These extra channels are also available on a USB 3 type A socket, so you could get speeds up to 10Gb/s on a type A socket depending upon how many channels are supported.

On a type C connector, which is symmetrical, there are another two channels on the other side of the connector so that you can plug it in either way around.
However, a USB type C connector has some configuration pins as well, amongst other things, these pins can be used to inform the devices which way around the cable is. When this is done, it can free up the extra serial channels thus allowing speeds of up to 20Gb/s. Note that this is only achievable when using USB-C to USB-C connections.

To complicate matters, not all implications of USB-C support these speeds, some only support USB 3.2 Gen 1 (5Gb/s), some support USB 3.2 Gen 2 (10Gb/s) and some support USB 3.2 Gen 2x2 (20 Gb/s).

So it doesn't surprise me when I see reviews quoting speeds of around 380MB/s and others quoting around 1800-2000 MB/s.

If that isn't confusing enough, some manufacturers of USB cables, you can probably guess which country, only have one extra set of wires for the high speed channels, what this means that if you insert the cabe one way, you get speeds of around 350-400 MB/s, but insert it the other way and you get speeds of 35-40 MB/s.

Don;t think there is a small enough 2tb nvme drive for the case