Hello Mycenius,
Thanks for getting back to us.
(a) is the file recoverable if you are offline and have some sort of catastrophic failure (like if your O/S won't boot) as per my post above,
This file contains your encrypted data since you were last able to connect to 1Password's servers. Recovering your account data is a matter of restoring your device and signing into 1Password. Once you are able to get back online, the most up-to-date data will appear once signed in.
As long as you are able to install 1Password 8 on device with the 1password.sqlite
file saved in the appropriate location, you will be able to continue to access your data with your account password and Secret Key.
(b) also just understanding what's involved in getting a copy of it and accessing it outside of 1PW (i.e. what would a potential bad actor need to do if it was an individual local breach or theft of data).
In case of a local breach, the malicious user would need to know both your account password and secret key.
As an aside is there any sort of inherent copy protection assigned to the 1password.sqlite
file - e.g. if someone tries to copy it is the master password required? If so is this true of macOS and Windows?
There is no copy protection on the 1password.sqlite
file itself, but as mentioned previously, it could only be decrypted with your account password and secret key. This is the case with all platforms, including macOS and Windows.
I hope this helps to answer your questions.