What would they have to offer Google in return for being granted this status? Would they have to ban NewPipe, for example?

Up to what a committee of 3 people (or in the alternate district court judge James Donato) believes this means, assuming the judge approves the proposed modification to the injunction in the first place

> Google may create reasonable requirements for certification as a Registered App Store, including but not limited to review of the app store by Google’s Android team and the payment of reasonable fees to cover the operational costs associated with the review and certification process. Such fees may not be revenue proportionate.

One appointed by Google, one by Epic, one appointed by the other two. All three will be barred from private communications about any of this with any parties.

Considering this is an anti-trust suit I suspect the judge would be extremely unamused if the committee members found that "must ban NewPipe" was a reasonable requirement.