It wasn't clear to me how the data was exported, but it seems the author built his own library: https://blog.kowalczyk.info/article/88aee8f43620471aa9dbcad2...
It appears that you can also export the majority of your data as shown here: https://www.notion.so/Export-to-PDF-or-markdown-ebb66c27de32...
It wasn't clear to me how the data was exported, but it seems the author built his own library: https://blog.kowalczyk.info/article/88aee8f43620471aa9dbcad2...