The GDPR states that "any information relating to an identified or identifiable natural person ... directly or indirectly, in particular by reference to an online identifier" is personal data (art. 4.1).
As far as Piano Analytics is concerned, the personal data processed is listed in article 6.5 Type of personal data (mainly the IP address and the identifier of the user’s terminal), and their usages in article 6.6 nature of processing of our standard Personal Data Processing Agreement (DPA).
In compliance with the GDPR definition (see above), all Piano Analytics data is considered personal data.