https://www.tablotv.com/setup-networking/#harddrive
We recommend Western Digital Elements drives and Seagate Expansion drives.
Most other brands/models are compatible, but avoid drives whose reviews suggest frequent disconnect problems.
This quote is in virtually every tab for each device, providing links directly to two (2) different vendors. Each link takes you to drive with options to various sizes, not a single drive.
Note: the Seagate site has a “find a retailer” button. On the very bottom of WD’s page there’s a link for “Distributors and Resellers” which takes you to a list of options.
The “compatible” link to a Community Topic is user’s experience, so you have to take it for what it is.