Another great dev for these old pianos is Modartt.
Pianoteq has several bundles of them, like the Karsten set, but you also get a few old grands for free with regular Pianoteq, even the cheapest Stage version.
Those so-called ‘rare pianos’ are indeed rare and old: a 1860 Swiss Grand and a 1922 Luthéal Piano. Definitely for aficionados of peculiar keys. Call me one. I love them.