For the Fire 10 2021 / Fire 10 Plus 2021, the model numbers are inconsistent across the specs page and the developer console.
The tablet specs page here: https://developer.amazon.com/docs/fire-tablets/ft-device-specifications-firehd-models.html
Lists the model numbers for the as: T76N2B / T76N2P
The developer console APK support page lists the model numbers (the page you see when viewing the APK binary details in your developer console):
Fire HD 10 (2021) - KFTRWI
- Fire HD 10 Plus (2021) - KFTRPWI
Which one of these is the correct model number for the released device?