Thailand would welcome you, same as people from (almost) all countries, IF you meet the Visa and COE (Certificate of Entry) requirements. Problem might be the lack of flights from Vietman. Also, if you don't mind me asking: Why would you? Doesn't Vietman have even much less cases? And doesn't Vietman still offer easy and free visa amnesty? I for one would be interested in going the other way - but who knows whenever this will be possible again.

Not too bad of an idea booking something now. Sure, there is uncertainties about what the exact conditions will be of entering in the future. On the other hand, almost all reputable airlines offer free date changes (only fare differences) on all their (even the cheap) tickets. They will not do so, once things are back to normal. So I am also thinking of booking now - so that I will then have a flexible ticket at a bargain price.

Yet someone wrote a review on Google praising that office services two weeks ago already. Did they have a trial run / soft opening, or are some people just plain stupid to review something that hasn’t opened yet - luring people to go to a closed office?

I get what you are trying to do. I am an organized person myself and also would like to limit the amount of time needed to spend inside an immigration office. Yet, I gave up on trying to get all the forms necessary prepared upfront. Simply because, whenever and wherever I go, there were different forms needed or their design and details varied. Every office does things differently. Hell, even every officer. A functioning website with reliable, current details and documents needed - forget it. So in the end there is just one approach: Go there. Listen to whatever they want. Get the forms they give you. Source the ever changing supporting documents they request from you. And then go again and hope for the best. A yes, and don't get smart and call them first. In my experience, just because someone tells you on the phone what is needed does not mean is (still) true on the day you go there.

Yes. And you actually have to do so in ASQ- expensive hotels dedicated to that.

What visa? What kind of extension? But generally: Yes.

No. But make sure you know what is required by the destination (or even transiting) country and the airlines.

Also, here is the link of the official form to use for change of visa from TR to any NON-Immigration Visa:

Yes. You can come into Thailand on a TR Tourist Visa and then change the visa in the country into a NON-B visa, that is, if your future employer is willing to provide the extensive documents requested by Thai Immigration for doing so. It is a little less paperwork involved when getting a NON-B outside of the country, but it is certainly possible inside the country as well. Enclosed, find a list of supporting documents required that was handed to me to change visa from TR for teaching at university on a NON-B. Handed to me by Chiang Mai Immigration Office.

Should you want to be working for a private company, be prepared to show a lot of additional documents as well, e.g. images of your future work place and crazy things like this. Also, requirements might differ from immigration office to immigration office.

With Thai authorities, bureaucracy meets inconsistency of requirements.