Can bitcoin accounts be imported? I have a DAT file which I generated using the backup feature of Bitcoin Core, I think. I'm not sure if it's possible ***to get Bitcoin Core to import the file so that it becomes a hot wallet.
Yes - from the bitcoin wiki:

"The original Bitcoin client stores private key information in a file named wallet.dat following the so called "bitkeys" format.

It contains:

keypairs for each of your addresses
transactions done from/to your addresses
user preferences
default key
reserve keys
accounts
a version number
Key pool
Since 0.3.21: information about the current best chain, to be able to rescan automatically when restoring from a backup.
The wallet.dat file is located in the Bitcoin data directory.

It is intended that a wallet file be used on only one installation of Bitcoin at a time. Attempting to clone a wallet file for use on multiple computers will result in "weird behavior"[1].

The format of this file is Berkeley DB. Tools that can manipulate wallet files include pywallet."

Also, there is a tool for viewing these files directly; https://code.google.com/archive/p/bdbvu/