Hello Arcade_queen0707,
When setting your your AirTags, you could set them up using either device you mentioned. You will want to make sure either device meets the system requirements for AirTags.
What you need
* An iPhone, iPad, or iPod touch with iOS 14.5 or iPadOS 14.5 or later and two-factor authentication turned on.
* Find My turned on.
* Bluetooth turned on.
* A strong Wi-Fi or cellular connection.
* Location Services turned on: Go to Settings > Privacy > Location Services.
* To be able to use Precision Finding and to see the most accurate location for your AirTag, turn on Location Access for Find My. Go to Settings > Privacy > Location Services, then scroll down and tap Find My. Check While Using the App or While Using the App or Widgets. Then turn on Precise Location.
Follow the steps in this article: Set up your AirTag using your iPhone, iPad, or iPod touch - Apple Support
As long as you are signed in with the same Apple ID on either device, you should be able to see your AirTags in the Find My app. This is helpful depending upon whichever device you have with you at that time.
Locate an AirTag or other item in Find My on iPod touch - Apple Support
All the best.