For those interested about Privium (in Dutch use translate), this blog shows a bit more about Privium (+lounges)
https://inhetvliegtuig.nl/privium-schiphol/
[not my blog]
According to them, business class checkin possible with:
Aeromexico,
American Airlines,
Cathay Pacific,
Emirates,
Etihad,
Finnair,
Icelandair,
Scandinavian Airlines,
Tap Portugal,
Swiss,
Lufthansa,
Qatar Airways
*they also mention Jet Airways which is ofcourse impossible as they have gone bust,
so hope Privium regulars can verify if this present list is accurate