For GDPR purposes:-
Kryptofolio with Tax contains anonymous crypto transaction information which is held only on the device. No personally identifiable information is used or stored.
All the users transaction records are NEVER shared nor analysed because there is no kryptofolio backend server they never leave the device and all calculations are done locally.
The only off box communications are anonymous to the Crypto Exchange for price data and Altcoin Exchange and to get the daily ECB exchange rates. These are all anonymous
The app does not use location services.
There is also a CLEAR DATA option that will remove all your data from the app.
There is an import transactions mode however the default settings are always 'Max Privacy'. Even in 'Blockchain Mode' transactions are looked up in large batches from www.blockchain.info so unidentifiable and you do need to specifically enable this mode as well.
Your can import transactions using a tool with QR codes and therefore not transmit them at all.
You can import and export transactions and calculations and reports via email you will have to specifically do this however.