Thank you for sharing. Very helpful as an assessment of how London handles it. I suspect different consulates will have different requirements. But maybe what you mentioned will be a good base line indicator.
Sometimes some grumpy old men give free advice. And that’s great. Doesn’t mean it’s always the best best or latest advice. Also, sometimes some already retired expats in Thailand think only they should have the privilege to stay in Thailand long term easily - and don’t like younger people to strive for the same. The transition to new realities was hard for that group and sometimes their nerves have been raw about that. Anyways, all good now. 😊
Either that, or you wait and hope for consulates in Thai neighboring countries to issue the DTV to non-residents there. Or a third alternative more in the gray area.
It always is a good bit messy und unclear at first with new things in Thailand. But they will muddle their way through in the end. The basics are clear. Most prominent aspect missing now is what qualifies as proof to meet the (partly unknown) requirements (especially on the Thai Soft Power side of things).
There is two sets of Thai consulates. Those already participating in the Thai eVisa system. For those you need to prove that you have residence within their jurisdiction. Then there is consulates in some countries that still do paper sticker visa with a personal appearance. The latter MIGHT issue you a DTV even as a non-resident. That varies from consulate to consulate and also depends on what visa you seek. For the DTV it isn’t sure / confirmed yet which (if any) consulates will do.
Your only potential alternative would be to get the DTV the old fashioned way / as a paper sticker visa following a personal appearance at a Thai consulate in a third country not participating in the eVisa system, yet. Although it is not really confirmed yet if and which consulates will be open to do that. Also, doubt it would make much economical sense to do such a detour.