no it’s needed for boarding the flight & they check it on arrival before immigration , best to print off the result too, I didn’t have time to print mine off & was fine till I landed in Phuket , they give you an email to send it to & print it off in the airport, but there were a lot of people on the flight the same and was a bit of a hold up to get through immigration due to waiting on the test cert being printed
You need to pre book your PCR tests for arrival & day 5-6 and upload picture of receipt for Thailand pass , you need the negative result 72-48 hours prior to flight depending on airline before you are allowed to board the flight
Yep Singapore is 48hours not 72 hours , I wouldn’t even want to do that kind of flight, on & off in so many destinations & so many long layovers , that is putting the %age of testing positive on arrival way above average , personally I wouldn’t take the risk