So it seems some TTB branches in Bangkok can open accounts for DTV holders, particularly DTV holders who work remotely! I can't confirm for the other category of DTV. They showed me a list of 4 items required, of which I was missing just one, which I've attached here. The other items are
1. Passport + DTV stamp inside
2. other ID from your country (license or ID card)
3. DTV proof like letter from employer/ employment contract/
4. The attached image - that's what I didn't have. What is that? It's related to residence though. They didn't care about my TM30.