Last week was a dream for the 18-year-old, who recently signed her first professional contract and made her first team debut for the Magpies.
The Lampeter-born youngster enjoyed a successful camp with her country's under-19s squad in Switzerland in April - but didn't expect to be told that this month, she'd be linking up with the senior side in Albania.
"I've got no words to describe it," Gregson told newcastleunited.com. "It's such an unbelievable feeling, and I think I'm still on cloud nine, because pulling that Wales shirt on makes me so proud.
"I couldn't believe my eyes when the email came through. I had to read it through about ten times to make sure it was real life, and just talking about it now I still cannot believe it's real.
"I phoned my dad first, and he was lost for words - we were both silent on the phone for a good ten seconds. We were speechless. My mam just burst into tears when I told her because it was all so unexpected for all of us."
She added: "I got my first cap (at youth level) in 2022, so to have gone from that to where I am now, it's amazing. This is the stuff you dream of as a kid, but now that I'm here I would love more
"To get a cap would just be unreal, but also soaking up the experience is the main thing and pushing myself.”
Growing up in a small town with a population of roughly 2,970 people, the clamour for a girls' football team wasn't there until Gregson's mother took it upon herself to set up a team.
The teenager couldn't be prouder of where she's from and what it means to represent her country.
"Little me would have doubted myself a lot to reach this point," she said. "So for this to now be my reality and see that the hard work has paid off is special. If I went back in time to tell my younger self, I don't think she'd believe me.
"We're such a small country and I feel like we are always seen as the underdogs, so for me to have the opportunity to go out there with the dragon on my chest and perform means so much.
"As a small nation to have achieved so much in the women's and men's game and have this exposure and see where we have come from is unreal."
While the percentage of people who speak Welsh is at an eight-year low, Gregson added: "For me, it's just about being proud of where I come from and who I am. Welsh is my first language, and being able to speak it so fluently is important to me and something that I find really special.
"A lot of the girls when I've been away on camps just don't speak Welsh, so I always try and encourage people to do so."
Cymru reached their first major tournament last year, with Lois Joel representing the Magpies at EURO 2025. Then-Liverpool defender Gemma Evans, now of United, also featured.
While they didn't progress to the knockout stages, securing qualification was a success and Gregson is looking forward to learning from the duo at both club and international level.
"I've always looked up to Gemma," she said. "She's been there (with Wales) from the start, and Lois has been with the national team for a long time too.
"Gemma has so much experience. I remember being a ball girl for some of the Wales games, and I was watching her play and thinking she is just brilliant. To now share a pitch with them and just pass a ball to both of them is something I would never have believed.
"They've both been great with me and so supportive since meeting them at Newcastle. When Lois introduced herself, she immediately told me that if I ever needed anything, to speak to her, and that made me feel so relaxed and settled."
