Looks promising. I been finding lots of money and asset management apps lately that are FOSS but they are all server side. I would like to find something like this that is completely client side only and you save your data to a encrypted file which one can easily sync to other devices with Syncthing and easily backup.
Client side will always be more secure than storing your data on a centralized server, even if you self host your own server. Or even if Ghostfolio created a flutter or tauri app and let users have the option to store their data locally in a encrypted file or on a server of their choice. That will be the killer app/service.