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.
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".
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/