Yes, there are quite a few. Some fanfiction platforms like Archive of Our Own likely have such works. You can search using the relevant tags to find them.
One idea could be that they meet during a political intrigue in King's Landing. Female Jon Snow, with her Stark-like honor, might initially be suspicious of Aegon Targaryen. But as they get to know each other, they find common ground in their desire to bring peace to the Seven Kingdoms. They could form an alliance that eventually turns into a deep friendship or even more, all while facing various threats from other power - hungry lords.
Power and politics are also common themes. A female Jon Snow would have to navigate the cut - throat world of Westerosi politics. Fanfictions often show her either rising to power, like how Jon Snow did in the original, or facing different challenges because of her gender while trying to gain influence and make a difference in the power struggles.
Jon Snow could potentially have allies like the Mormonts. They have always been loyal to the Starks. Maybe even some of the Dornish houses might side with him. They have their own reasons to oppose the current power structure in Westeros. And of course, his friends from the Night's Watch who left with him or believe in his cause could be his allies in this conquest. He might also gain the support of some of the maesters who see the value in his leadership for the future of Westeros.
Daenerys Targaryen could be one to help. Since she has experience with dragons, she could give Jon Snow advice on how to care for the egg and hatch it.
It could be a young and untainted Frey. Maybe a niece or a cousin of the more infamous Freys. One who has not been involved in the past atrocities committed by her family and has a more noble heart.
Daenerys Targaryen is often paired with Jon Snow in such fanfictions. Their combined power and the potential for a different kind of relationship makes it a popular choice among writers. Another character is Arya Stark. Their sibling bond can be explored in new ways when Jon is reincarnated, like Arya helping Jon with her assassin skills in a different plot line.
The North would surely support him. They have always seen him as one of their own and a great leader. Also, the wildlings might back him, considering he has a history of working with them and understanding their plight. Davos Seaworth would most likely be on his side as well, given his loyalty to Jon in the past.
Daenerys Targaryen is often paired with Jon Snow in these fanfictions. Their connection in the original series, along with their both being strong leaders, makes for an interesting dynamic. They could rule Westeros together in a new era of peace and prosperity after Jon's rebirth.