Thank you very much for the suggestion. At the moment, the app relies on the Google ecosystem and is designed to be installed through Google Play. To help protect the chart data from unauthorized copying or distribution, the app performs integrity and installation-source checks when it starts. Because of these security requirements, I currently don't have plans to publish the Android version on alternative app stores such as F-Droid or Neo Store. However, I really appreciate the suggestion and your support. Thank you!