I’m sure others here have noticed this because it’s quite obvious and Sebald was famously into Nab, but there’s a direct reference to Chapter 8 of Speak, Memory at about 20% of the way through WG Sebald’s Austerlitz.
I only recently remembered this white pall over the manse,” said Austerlitz, “when I was reading the reminiscences of his childhood and youth by a Russian writer who describes a similar mania for powder in his grandmother, a lady who, although she spent most of her time lying on a sofa nourishing herself almost exclusively on wine gums and almond milk, enjoyed an iron constitution and always slept with her window wide open, so that once after a night of stormy weather, she woke up in the morning under a blanket of snow without coming to the slightest harm.
Cf Chp 8 of Speak, Memory:
A box of boules de gomme, or a glass of almond milk were always within her reach, as well as a hand mirror, for she used to repowder her face, with a large pink puff, every hour or so, the little mole on her cheekbone showing through all that flour, like a currant. Notwithstanding the languid aspects of her usual day, she remained an extraordinarily hardy woman and made a point of sleeping near a wide-open window all year round. One morning, after a nightlong blizzard, her maid found her lying under a layer of sparkling snow which had swept over her bed and her, without infringing upon the healthy glow of her sleep.
This is far from the first VN allusion in Sebald but I saw only one post about this particular allusion and the poster didn’t locate the source in SM.