Are all of these pollsters conducting Trump/Biden numbers and not releasing them or are they just not asking that. Plenty of pollsters seem to have both GOP and Dem primary polls but aren't releasing Trump/Biden head to head.
Thankfully it looks like CBS did a GE poll too, but they are withholding the results I guess. Some of the questions are missing from the PDF
These CBS News/YouGov surveys were conducted between September 15-24, 2023. They are based on representative samples of 1,011 registered voters in Iowa and 943 in New Hampshire.