In 2020, Nuviad listed the following surveillance advertising companies as data sources:
Google, MobPub (back then owned by Twitter), AOL/Yahoo, Smaato, OpenX, Amobee, Pulsepoint, Rubicon, Inneractive/Fyber (Digital Turbine), Avocarrot/MobFox (Glipsa, Germany), Axonix, Altitude Digital, Opera Mediaworks.
https://web.archive.org/web/20200511011617/https://nuviad.com/
As of today, Google lists Nuviad as a vendor "eligible to receive bid requests compliant with US states privacy laws", i.e. sends data to them:
https://support.google.com/adsense/answer/10634320?hl=en