Rees-Zammit is in contention to make his first appearance for Wales in two years after his unsuccessful switch to American football.
The 24-year-old had spells with the Kansas City Chiefs and the Jacksonville Jaguars, but did not play a competitive game in the NFL before signing for English Prem club Bristol in August.
After participating in the NFL's International Player Pathway (IPP), Rees-Zammit initially signed with Kansas City, but was cut after failing to impress during pre-season appearances in 2024.
He joined Jacksonville and spent the 2024 season as part of the franchise's practice squad without making a regular-season appearance.
With his time in the United States at an end, Rees-Zammit has linked up with his Wales team-mates in Cardiff this week as the build-up starts to November Tests against Argentina, Japan, New Zealand and South Africa.
"It feels amazing to be back in rugby. I went out there and tried it out but I am really happy to be back," he said on Wednesday.
"It is great to see all the boys again and there is a new coaching staff, which is great. All the boys are loving it and we are ready to rip in.
"This is the first time I have been on this field for 18 months and it feels weird. It is great to see so many fans support us because it means so much to us."
Rees-Zammit trained away from the main group as he recovers from a toe injury sustained playing for Bristol earlier this month, but the wing is optimistic of being fit to take on Argentina on November 9th.
"My foot is feeling really good. I have just been running the past couple of days and trying to get it ready for next week but it is looking positive," he said.
The confident Rees-Zammit's presence has been a boost to Wales after a disappointing spell for the national team, according to team-mate Freddie Thomas.
"I was in the Gloucester Academy with him, so it's always nice to have an old friend back in the group," Thomas said.
"He's definitely bigger, a lot of weight in terms of muscle, but still has his speed.
"He's an unbelievable player and definitely not shy. He has that confidence and X-factor we need because there were times last year where it was probably a quiet group, with not many boys prepared to speak up in meetings and call each other out."