You do not need to rely on the read and write speeds provided by a hard disk, USB flash drive or SD card manufacturer. It is quite easy to figure out by yourself the sustained read or write speed of any storage device in Ubuntu.
Make sure your storage device is plugged in, has a filesystem and is mounted under Ubuntu. Let us assume it is mounted at
$ dd if=/dev/zero of=/media/my-usb-disk/speed-test-file bs=100K count=1k
$ dd if=/media/my-usb-disk/speed-test-file of=/dev/null bs=100K count=1k
Remember to delete the temporary file after the test is done:
$ rm /media/my-usb-disk/speed-test-file
Some read-write speeds I found on my devices:
Tried with: Ubuntu 22.04 LTS