Wigan striker Moore headed Wales into a first-half lead before Juraj Kucka equalised after the interval to earn Slovakia a 1-1 draw.
Moore worked as a part-time swimming pool lifeguard while his non-league travels took him to Truro and Dorchester.
The 27-year-old would go on to play for Viking in Norway, Yeovil, Forest Green and Ipswich before becoming a hit at Rotherham and Barnsley and making his first competitive appearance for Wales in Trnava.
“Kieffer was a handful all night,” Giggs said of the 6ft 5ins striker whose scoring exploits in south Yorkshire secured a reported £3million summer move to Wigan in the Sky Bet Championship.
“He gives us an option. I am really pleased with the goal and overall really pleased with his performance.
“I thought he did really well against Belarus (in a friendly last month), he occupies the two centre-halves and he gives us a different option.
“He took a few knocks, but it was a real competitive game without being too dirty.”
The draw leaves the race for qualification in Group E delicately balanced with Wales trailing second-placed Slovakia by three points and Hungary by two, but having a game in hand on both.
Wales, who beat Slovakia 1-0 at home in March, will finish above them on their head to head record if they end on the same number of points.
Croatia are three points clear of Slovakia and favourites to take the first of the two qualifying places after beating Hungary 3-0 in Split on Thursday.
“Obviously now we have a better head to head than Slovakia but you still have to capitalise on that,” Giggs said.
“It’s never easy away from home and it’s always fine margins.
“It could have gone either way and it was end to end, a good game for the neutral. Overall I’m happy to get the draw because we were under pressure at times.
“But we probably created the better chances. We could have won it, we could have lost it.”
Wales have little time to recover from a pulsating encounter before playing Croatia in Cardiff on Sunday.
Giggs hopes to have Aaron Ramsey available after the Juventus midfielder missed the Slovakia draw with a groin problem.
Gareth Bale is expected to play after needing lengthy treatment in the final minute in Trnava, but Ethan Ampadu is doubtful after being substituted near the hour-mark.
On Bale, Giggs said: “It was on the far side so I didn’t really see what happened, but I was a little bit worried when the referee called for a stretcher.
“He’s fine. He took a knock but he should be OK.
“Ethan was feeling a bit tired and a bit leggy with his lack of game-time (at RB Leipzig).
“We just have to assess him because he’s not playing games at the moment. We’ll have to wait and see, but it might be too quick a turnaround for Ethan.”