In old houses there is no intercom. Only a doorbell from the „house“ door and a push-button to open the door.
Will the NUKI opener also work in this environment?
Yes
See the last question in the FAQ on https://nuki.io/en/opener/ :
Can I also control my electric garage door with the Opener?
In principle, the Opener can be used to control virtually every door. During the setup process using the Nuki app, you have the option to select other doors (e.g. garage, garden gate, switch) in addition to conventional intercom systems. You will find clear instructions on how to connect the Opener to any switch in the app.