Palliative care is officially part of the Thai government hospital services, and in reality, the situation is not far behind. Several government hospitals have palliative care departments, and some even have dedicated doctors and nurses for this purpose. However, hospice services are rarely available. Most end-of-life care patients in Thailand are cared for by relatives at home. I assume you may not have such relatives, but perhaps you can hire a full-time nurse to act as a ‘relative’ and receive palliative care services from government hospitals.
A quick search shows that Pathum Thani Hospital has a palliative care service guideline, which strongly implies that they offer such services. This kind of care often involves a network of government-run primary care units (known as โรงพยาบาลส่งเสริมสุขภาพตำบล, formerly called สถานีอนามัย — you can ask any Thai person you know about them) that provide home visits. These services almost always include morphine tablets, with dosages adjusted to effectively control pain and discomfort. Most of these services also provide a slow-injection device for subcutaneous morphine administration when oral medication is no longer possible. However, they are legally not allowed to administer a lethal dose.
Another quick search shows that Thammasat University Hospital runs a hospice service under the name Thammasat Thammarak Hospice and Palliative Care Center, located in Pathum Thani as well. Their contact number is 095-464-9783. You might consider reaching out to them.
May you find peace and comfort during this stage of life.