The Wales players were silent during the anthems again on Sunday before victory over the UAE.
Giggs said afterwards: "It's a personal thing.
"The British anthem is the same for a Welshman, Scotsman or an Englishman.
"It's difficult but it's not an issue for us. It might be for other people but, once the game starts, we're all pulling in the same direction and I think that's the main thing."
Team GB's final group game against Uruguay takes place at Cardiff's Millennium Stadium where Giggs, Bellamy and Allen can expect a hero's welcome.
The national anthem may not be so warmly received in the Welsh capital.
"I hope it won't get booed and I hope the fans will get behind us as they have in our first two games," Giggs said.
"It will mean a lot to all of the Welsh lads to play in our own stadium, our own back yard so it will be a great occasion."