Pitbulls are a very popular breed here in Phuket. The following documents from the Office of Agricultural Affairs from the Royal Thai Embassy clearly states that “No dog breeds are banned from importation”
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fPdh6NtO/About-Thailand/Bringing_Pets_to_Thailand/All_Airports_-_Instructions_for_Bringing_Dog-Cat-Rabbit_into_Thailand_from_the_USA_(Revised_30Jan2025).pdf
There are also the contact details for the Animal Quarantine Stations (who I believe issue the import licenses) towards the bottom of the file. I would suggest giving the one in Bangkok a call and asking.