If someone could make this device and run it cost effectively, what incentive do they have to sell it? Last I checked, the only place to make money on crypto was certain areas in China with very low electricity costs.
It does seem really sketchy though, they are all over the place. They say they use Proof of Stake, but BTC is not PoS. And not sure how that ties into this little gem: "Node earns Incognito’s native coin, Privacy (PRV)" =)
Ads are something for easier understanding. I went trough wp, it says that is someone use their sidechain for private BTC or ETH transaction validator will receive a transaction fee in the same currency.
And regarding ROI, here you are right, it's impossible to evaluate how much you can earn with this node until the token is on open market.
The same was with BTC, the same was with ETH and so on. You never know which project will be next one ;)