Share AirTag

No.

At present an AirTag’s location can only be viewed within FindMy on a Trusted Device of the paired AppleID.

However, you CAN read a recent Apple announcement concerning upcoming changes to this feature here:

(about 2/3rds of the way down the page within “Additional features in iOS 17” )

iOS 17 makes iPhone more personal and intuitive - Apple (MY)

This is the current status, from: 'How to reset your AirTag' --> How to reset your AirTag - Apple Support

"An AirTag can be associated with one Apple ID. If you want to use an AirTag that someone else has used, they need to remove the AirTag from their Apple ID first. "

Yes. I believe he will have to enable Family Sharing for an AirTag to be shared on multiple devices before IOS 17. He'll also most likely have to add iCloud+ for more storage. Otherwise, others that are near his tag that he didn't include in his Family Sharing will get the alert that they're being followed, and they can only pause it for 24 hours. After IOS 17 he can share the AirTags with up to 5 more devices. iPhone 15 or newer is required for precise location.