Yesterday I applied for the Thailand Pass for me and my spouse.
Prepared all the documents beforehand in jpg-format.
To make a jpg document from a pdf file you can use SmallPDF or other online programs.
For the proof of vaccinations I used the European Vaccination Certificate + I extracted just the QR-code using Paint-software to make a separate document of this.
In the form, you can use the same European Vaccination Certificate for the 1st and 2nd dose and also send the same QR-code twice. Just use a different date.
Used a Gmail-account for the email.
Submitted the completed document and about the same time as I received the mail with the 6-digit code, I already received the approval QR-code. Maybe seconds later ...
The same for the documents for my spouse. Seconds after submitting I already received the QR-code.
Maybe I was lucky. ????