Disclaimer: I don’t work for Nuki. What I write below is my understanding of the system.
If I understand correctly, the lock itself only has bluetooth communication capabilities. If you want WiFi you have to use the additional Bridge device, correct?
Correct. The Nuki Lock (and Opener) only have Bluetooth. The Bridge does what the name says and bridges Bluetooth and Wi-Fi, allowing Lock and Opener to be reachable through Nuki’s services on the Internet (or through an HTTP API in the local network).
Will I be able to download the app? (unlikely)
Depends on if the Company specifically asks Google/Apple to delete them (and how Google/Apple handle defunct companies). In Android’s case, you can grab the APK and back it up for later use (as long as Android itself doesn’t advance too much to make it fully incompatible and prevent it from being reinstalled).
- What can I do, without the app?
If you have the Bridge, you can use the HTTP API to talk to it via the network and all functions documented there: Bridge HTTP-API (checking lock status, locking, unlocking, …) There are existing software libraries that make this easier (PyNuki for example) and even software that includes functionality that relies on this API (Home Assistant for example).
You can also write your own Bluetooth app to talk directly to the lock using the BT API and its commands:
Even if I have the app, can I still:
- Use the bridge (HW or Android) to connect to lock remotely?
You wouldn’t be able to use the app to go through the Nuki servers to lock/unlock remotely. You would have to write your own interface/app to talk directly to the Bridge. (e.g. a Home Assistant server in the same network that you can access remotely, …)
- Assign/revoke permissions to new users?
With the Nuki infrastructure gone, there would be no “users” on their end to add/remove. If you still have the app, you can probably still authorise it to the lock locally (it’s all BT) and remove other authorised BT devices/apps. If you’re using your own solution to locally talk to the Bridge with an HTTP API, access management of that solution would be up to you (e.g. Home Assistant users, …).
With the Nuki infrastructure gone, the Bridge would have no way of sending you notifications through it. You would probably need to leverage the Bridge HTTP API and set up local infrastructure that does that. (e.g. local server registers a callback with the Bridge and handles sending the notifications when that callback occurs).