The West Africans appeared on course to end a run of five consecutive friendly defeats after substitute Caleb Yirenkyi gave them the lead midway through the second half.
However, Lewis Koumas struck in stoppage time, heading home from a superb Neco Williams cross to deny Ghana a morale-boosting victory.
Ghana arrived in Wales eager to build momentum ahead of their World Cup opener against Panama later this month, with Queiroz using the encounter as an opportunity to assess his squad before they head to a training camp in the United States.
Despite conceding late, the Portuguese coach remained optimistic about what lies ahead for his team.
"I believe with the next programme of 10 days of training sessions, we will make a lot of progress and be much more consistent," said Queiroz as quoted by The Guardian.
"The win was in our pocket, but it's time to learn. When we are winning 1-0, there's no way that we can let the win escape from our pocket, but unfortunately it happens."
Manchester City forward Antoine Semenyo was rested as a precaution, with Ghana unwilling to risk one of their key attacking players just weeks before the tournament begins.
Wales head coach Craig Bellamy believes Ghana remain a dangerous side despite their recent struggles in friendly matches.
"You have a tough group and a new manager, but you're a dangerous team in transition because of the speed you always have in the top line," Bellamy said.
"Your tournament is going to be decided by that game against Panama. If you win one game, you might get into the knockout stage."
Queiroz admitted Ghana still have work to do, particularly with injuries ruling out several important players, including Mohammed Kudus.
Ghana will now turn their focus to final preparations in the United States before beginning their World Cup campaign against Panama.
