The Magpies will face last season's beaten FA Cup finalists in the fourth round of the competition, after defeating Stoke City Women 5-0 in the previous stage at Gateshead International Stadium.
Galloway, who scored a brace in that victory over the Potters, has experience of playing Manchester United, having faced the Reds in the Continental Tyres League Cup during her time at Durham Women.
"I think in the FA Cup, it's all to win," declared the striker. "We have got nothing to lose so we have got to just go for it.
"Playing one of the best opponents in women's football is going to be a tough test but we have just got to go at it and see that we have nothing to lose and give it our all. Anything can happen in a cup game at the end of the day.
"When I have previously played Manchester United, in the Conti Cup, we (Durham) have taken it to penalties and won. Anything can happen.
"It's just who is up for it most on the day. Hopefully, we bring it and give everything we have got and see what happens."
The Magpies come into the match on the back of a huge 7-0 win over Halifax Women at the weekend.
Despite not adding to her tally of 14 goals this term, the prolific forward was pleased for the Lasses who got on the scoresheet to start 2024 positively.
"I thought everyone was up for it," she said of the match. "It didn't look like we'd had a break before Christmas and it is great to go into the new year with a 7-0 win.
"It was a big scoreline and credit to all the girls who scored. It was a big scoreline and it doesn't matter at the end of the day (whether I scored or not). You can't score every week!"
Looking ahead to the 12:00 GMT kick-off at Leigh Sports Village on Sunday, Galloway says that fixtures such as this are what the FA Cup are all about.
Despite the distance between the sides in the football pyramid, she is confident the Magpies have more than enough to trouble the hosts in their own backyard.
"Manchester United are one of the teams you want to draw in the cup games," she said.
"It's good to see where you are at in comparison and it's great to play against some of the best opposition. That's where you want to be in the future.
"I think everyone is level-headed. No one is overthinking it, even though they are one of the biggest clubs. Everyone is just really excited to play Manchester United, but I don't think anyone is overwhelmed by it.
"We have got plenty of different goalscorers in the team and we can score a lot of goals. We haven't conceded many goals either, which is a good thing.
"The chemistry in the team keeps growing and growing every week and you can see that. We link up really well together and we have gelled really well as a team.
"I think it is perfect timing to play Manchester United and I do think it will be an exciting game. I think everyone is up for it and raring to go - especially in the FA Cup.
"Everyone wants to play in the FA Cup and everyone is excited for it."
