The dietary laws seem to represent the spiritual lesson of not making ourselves unclean through fellowship with unclean people (2 Corinthians 6:14-17, 1 Corinthians 7:14).
I've never heard that analogy concerning the dietary laws, so I will need to look into it before I comment.
11He saw heaven opened and something like a large sheet being let down to earth by its four corners. 12It contained all kinds of four-footed animals, as well as reptiles and birds. 13Then a voice told him, “Get up, Peter. Kill and eat.”
16This happened three times, and immediately the sheet was taken back to heaven.
19While Peter was still thinking about the vision, the Spirit said to him, “Simon, three a men are looking for you.
And Peter himself points this out in the very next chapter:
"9“The voice spoke from heaven a second time, ‘Do not call anything impure that God has made clean.’ 10This happened three times, and then it was all pulled up to heaven again.
11“Right then three men who had been sent to me from Caesarea stopped at the house where I was staying. 12The Spirit told me to have no hesitation about going with them." - Acts 11:9-12
See it?
The unclean creatures represent people.
The law against eating unclean foods signified not having intimate contact with unclean people who will make you unclean and unfit to approach God in worship.
(The 'eating' of unclean food is what signifies the intimate nature of contact. This is not about casual association with unclean people, because if it included that Paul says you'd have to leave this world-1 Corinthians 5:9-10.)