Yeah! I didn't know of this sonata before. Very good performance by one of my favorite pianists.
About pedalling?
It's really difficult to say. At least on this recording, it's a lot of reverb, and knowing the label and its engineers a bit, just from listening over the years, I'd have to guess some of it was done deliberately, by using a microphone in a reverb chamber.
The Alberti bass sections, if I were forced to try to recreate the sound Brendel recorded, I'd be using about 1/2-1/4 pedal on the downbeats, but very careful to not blur anything.
It would be interesting to see how the recording was made: beautiful piano, and the reverb, I'm guessing, was made live from a chamber, mixed in with the various other microphones including the sound of the room.
It wouldn't surprise me if, at the end, there were a dozen or more microphones used to create this sound.
Perhaps not.
I can't really give advice on how you should play this, having never played nor heard this one. (edited: But I will now play this, so thanks for the tip on a pretty neat little sonata of Haydn). I do about a handful of the very last Haydn sonatas, every now and then, and I'm happy with having playful or sometimes even dramatically accented staccato notes. It's almost like funk music, this sonata, and others: the emphasis is always tending to the first downbeat, the "one" of every phrase.
It's hard to tell how Brendel performed them, because of the long tail of the reverb. But it does seem that Brendel agrees with me about phrasing: his attack is actually pretty fierce, at the beginning of each phrase.
EDITED: I did just now read through this sonata at the keyboard. Astonishing. And, actually, not that easy to play. My impression after one reading of it at the piano is that the longer lines or phrases are the main challenge of the piece. Everything appears to require a kind of propulsion from the inside logic of the piece.
For me, since it was my first time playing it, I was inclined to be a bit playful about the accent marks on the score, but the pace of the piece is rather quick, so it hardly matters in context of the larger musical phrases and statements Yes, it matters, of course, but I think there's plenty of room to interpret in different manners.