As for the Florida documents trial, Article II, Section 2 says the President “may require the opinion, in writing...”
This was obviously so a President could ensure he would not get “stabbed in the back” later if something went wrong. Obviously, a President might need to retain such writings if he wanted to hold public office again.
From what I have heard, the Florida documents were primarily related to the Russia Collusion hoax. There was a high-level CIA document that was found to be missing that seemed to have people in a panic, but it was not found in the raid. These documents were all classified to protect the guilty parties, not to protect national security. There were no documents with the nuclear launch codes. That reporting was another hoax. Trump had the authority to declare all of these documents declassified while he was president and he had authority to have classified documents under the Presidential Records Act (44 U.S. Code Chapter 22). Trump had worked to implement proper storage security, had security inspections and even implemented recommended upgrades.
My belief is that they thought Trump had the missing CIA document that they are panicked about (and he still may). I also think that the upper level FBI people knew Trump was planning to sue them and others for the Russia hoax and they used the SWAT raid to take his evidence.