Yes, the project started in February 2017, so it's been a while and the app is very mature and frequently used by many citizens (full disclaimer, I was leading the development of the app and the backend from the beginning until almost two years ago).
Do you know why no other, more open, two factors are being introduced in DigiD auth? I'd rather use my U2F fobs, like I can almost everywhere else. Some people like TOTP.
