This is the only official way I know of to register trips. What it means or not means is not for me to decide. Your vaccination status is irrelevant for travelling by road at present, as very few people have been fully vaccinated.
When you work for a company you can join social security. A portion of your contribution goes for medical cover and a portion for pension. After you leave the company you can continue with your contributions. It is also available to foreign employees.
the problem is with a vax and negative test you can still get infected on your way here. I do believe we will get to a 3 day isolation after a negative test on arrival. The problem is that they want to vaccinate more Thai people in tourists areas before opening up. It is however not going at any pace at present.