Well is this not just a fine pickle? Is it Kosher?
Muslims have some good ideas, just as the stopped clock is right time twice a day. They have a concept of right and wrong that is different. Depending on who is writing about it, it is more of a five point scale: required, permitted, neutral, wrong, absolutely forbidden. so Halal are permitted.
So the food rules are essentially the same as the old testament, and in a hot dirty country are about what is necessary to stay healthy. Now we have cleaner conditions, refrigeration, we generally understand disease, bacteria, blood borne parasites, and similar disease agents, these rules are just well archaic and followed out of blind faith.
So I will leave it to you to look up those rules if you like; Leviticus 11, Deuteronomy, Torah, and or Quran.
Now let us consider pizza; first you have crust, grain; then cheese, dairy, then meat. In what alternate reality would these be acceptable in one dish? He was only concerned about the meat. Pizza, with halal meat violates about four other rules. With such a ignorant question as "is it halal?", the answer to such ignorance must always be yes, for you do not know the rules, why should I, an atheist or christian for that matter.
In one rule set it is not permissible to mix grain, dairy or meat. Even a sandwich with butter and meat is not halal, you idiots. Pizza, is a vegetable according to a US senator. Pizza is a mix of all three also.
For meat to be halal, the animal (not pig or rabbit) must die from a slashed throat, which is not legal in either the US nor Canada for humanity rules. No commercially produced, government inspected meat is halal. So imagine the outcry when this is recognized. On one side there is the animal right, on the other the Muslims. Oh well. The Kosher Rabbis know this and look the other way in the slaughter houses, for the animal is just stunned then the throat is slit, as the rabbis pray.
Halal pizza and halal meat is like a bank looking after the customers interests. Just does not happen. You can think that if you like, but you need to get hold of something solid and give your head a real good shake. It is like believing that there is an all knowing, all wise old man in the sky to call god.