Volume 1 earned several raves on this site, and vol. 2 is now on the horizon. This one is comprised of several single-movement pieces as well as a very early Sonata #1 - Gernsheim was in his teens. Amazon USA shows 5 Feb release, don't see it yet at Amazon UK or Presto.
https://smile.amazon.com/Piano-Music-2-Gernsheim-Barnieck/dp/B08QRZ7R5M/ref=sr_1_147?dchild=1&qid=1609114312&refinements=p_n_date%3A1249114011&rnid=1249111011&s=music&sr=1-147 (https://smile.amazon.com/Piano-Music-2-Gernsheim-Barnieck/dp/B08QRZ7R5M/ref=sr_1_147?dchild=1&qid=1609114312&refinements=p_n_date%3A1249114011&rnid=1249111011&s=music&sr=1-147)
I'm guessing his published piano sonata (Op.1) is something like piano sonata no.4, then.