This site introduces unknown Emanuel Bach (C. P. E. Bach).
ChatGPT4o writes as follows (please note that it may not be accurate):
Emanuel Bachʼs Sonatina in D Major Wq. 63-9 (H. 294) is one of his works that showcases his diverse musical style. This sonatina, while influenced by his father Johann Sebastian Bach, pursues its own unique expression and is considered an important piece during the transition to Classical music. It is characterized by the bright and lively key of D major, combining flowing melodies with rhythmic elements. Emanuel Bachʼs compositions are notable for their rich emotional expression and improvisational qualities, and this sonatina is no exception. In particular, the changes in dynamics and use of ornamentation in his music leave a fresh impression on the audience. This piece continues to be performed today as an example of his keyboard technique and musical innovation.