Hello daquezada,
Thanks for reaching out to Apple Support Communities. We see you have some questions about passwords and using iCloud Keychain with your Apple TV. iCloud Keychain is not compatible with Apple TV. However, we did find something else you can do:
Use the iOS or iPadOS keyboard to enter text on Apple TV - Apple Support
Use the iOS or iPadOS keyboard to enter text on Apple TV
• If you prefer not to enter text using the Siri Remote, you can set up a nearby iOS or iPadOS device to share its keyboard whenever a text field appears on Apple TV.
• The iOS or iPadOS device must meet certain minimum requirements. See the Apple Support article System requirements for Continuity on Mac, iPhone, iPad, iPod touch, and Apple Watch.
Set up an iPhone, iPad, or iPod touch to enter text on Apple TV
1. Make sure the iOS or iPadOS device and Apple TV are both signed in using the same Apple ID.
2. And that Bluetooth® and Wi-Fi are enabled on the iOS or iPadOS device.
Upon further reading in the Apple TV User Guide, we found some additional pages which talk about getting those app passwords from your iPhone or iPad to the Apple TV. Take a look at the below pages:
Set up accounts for other apps and channels on Apple TV - Apple Support
Use an Apple device to sign in or make purchases on Apple TV - Apple Support
For additional assistance with any of the above, contact Apple Support for Apple TV.
Apple Support
Select Choose a Product > Show > Apple TV > Setup & Configuration
Regards.