The Transcend JetDrive Lite is as close as you can get to upgrading the internal storage on your modern MacBook Pro, but hard drive-like speeds limit its uses.
1TB Transcend JetDrive Lite 330Designed for the 2021 16-inch MacBook Pro and 14-inch MacBook Pro, the Transcend JetDrive Lite 330 is a small chip of solid-state storage that slips into the SD card reader to expand capabilities. You’ll hardly even notice it is there while you can add up to 1TB of additional storage.