With Steve Clarke missing eight players from his original squad through injury, illness and suspension, the 23-year-old Hibernian defender was handed his international debut during the goalless draw with Ukraine.
Porteous turned in a terrific performance as the pool leaders, following home wins over Ukraine and Republic of Ireland, kept Oleksandr Petrakov's side at bay to earn the point required for promotion to League A.
Scotland also secured a place among the second seeds for the Euro 2024 qualifiers and a guaranteed play-off spot to qualify for that tournament should they need it.
Stand-in skipper McGinn said: "It feels amazing.
"We were up against it, we had illness, we had injuries and the travel and three games in six days, so a lot of circumstances were going against us, but we stood tall and showed good character in the team.
"It shows you the strength in depth we have, we have top players around the country whether that is in the Premier League or in Scotland.
"We like to talk our game down, we like to talk our own players down, but we need to try to get away from that and try and support every player that comes and plays for the national team.
"There were a few boos when Ryan's name was read out the other night, which isn't acceptable and I was delighted for him.
"He has proved a lot of doubters wrong and, if it wasn't for him and Jack Hendry, we might not be in pot two for the Euro draw and in League A.
"So delighted for Ryan to shut a few critics up and hopefully moving forward we can get behind everyone no matter who they play for or how they are as a player."