I just applied for mine but I was being treated at a hospital 2-3 times a week for 3 months before I left to apply for the DTV Visa. I sent the medical certificate that has the treatment plan on it and my future appointment slips to the immigration office at DC before leaving bangkok and they said that was sufficient
If you are going to be receiving medical treatment for any issues you have while living in Thailand you might try going that route on the DTV. That’s what I am doing for the treatment of my chronic pain and dry needling
it’s not based on the airline, it’s based on your travel history and the immigration agent. It is not uncommon for them to ask for where you are staying (hotel, Airbnb, etc.) and when you are leaving the country (follow on travel). They normally don’t ask for proof unless you show difficult to give information or if they have suspicions that you are abusing the visa exemption based on your travel history.
an international micro chip! In the US out microchips require a different type of chip reader so when you go to the vet make it is an international chip