How to include Google Interest Groups in Publisher-run Protected Audience API?

[wojciech-bialy-wpm]

We're now testing Protected Audience API (PAAPI) on our websites. At the moment, we've split PAA-enabled inventory into two sets:

• on 50% of the inventory, PAAPI auction is initiated by the Google Ad Manager, and includes component auctions provided by the publisher
• on the remaining 50% of the inventory, PAAPI auction is initiated by the publisher, and runs partly in parallel to header bidding / adserver calls

This test setup is described in the following issue to WICG/Turtledove github: https://github.com/WICG/turtledove/issues/851

The purpose of this test is to ascertain both revenue and UX impact of sequential and parallel PAAPI setups.

However, validity of the test depends on executing both types of auctions with the same set of buyers. This is ensured for our partners (using the same component auction configs in publisher-initiated and Google-initiated top level auctions), but is there a additional 3rd party demand from Google Ads, that is used in Google-initiated top level auctions? If so, can You provide a Google component auction config we can use?