There's a cool article from Jethro B. in the latest Road & Track (February-March 2024), where he visits Pininfarina S.p.A.'s wind tunnel and they put two cars in there to get some aero results. One of them is Pininfarina Battista (the other one is Miura SV).
The facility has rolling floor and for this test they measure with wind speed ranging from 100 kph to 140 mph and repeated at 5° yaw angles.
Their Battista was one of 5 Anniversario cars, equipped with the Furiosa package (more aggressive splitter and diffuser). The results were as follows:
drag coefficient: 0.34 Cd
downforce:
1,102 lb (500 kg) at 217 MPH (347 kph) limited
=
260 kg at 250 kph
aero split above 125 mph (200 kph):
15% front / 85% rear
They didn't say which one of the four set angles the wing was at, but I assume it was the most aggressive one before it becomes an airbrake.
Given the difference of the aero between Battista and Nevera, it makes me think the Rimac generates more downforce. Battista is primarily a low drag car with single movable wing, whereas Nevera has not only much larger wing, but also three active flaps (two in the front, one in the diffuser). I'm thinking it wouldn't need those if the downforce was nothing to write home about.
Rimac says that the downforce increase between the long range mode and the track mode is 326%.
For context, LaFerrari claims 140 kg at 250 kph in their low drag mode. Assuming Nevera is even more slippery, being an EV where range is important, I could see it being somewhere around 380 kg at 250 kph in the most aggressive setting.
The Miura results were pretty funny, but that's another story.