Some desktop and browser-based password managers support storing/generating TOTP codes as well, essentially replacing the need for a separate mobile authenticator app. But since you cannot scan a QR code with them, you need to manually pass the secret key to them as a text.
Many websites that support TOTP 2FA show the secret key along with the QR code during the setup process. Something like "Can't scan the QR code? Use this secret instead". It could be helpful to have this in Lunch Money as well.
Available workarounds: 1) use companion mobile apps for desktop-based password managers. 2) Get the secret key by inspecting the QR image URL