Sure, there are. Some fanfictions in this category might show how Fem America challenges Pirate England's authority on the ship at first, leading to a series of comical and tense situations. As the story progresses, they come to understand each other better. It's a really interesting genre within the Hetalia fanfiction world, with a lot of room for creativity and different interpretations of the characters.
Yes, there are quite a few. You can start by looking on popular fanfiction websites like Archive of Our Own. Just search for 'hetalia fem america and pirate england' and you'll likely find some interesting reads. Some might focus on their adventures together on the high seas, while others could explore a more romantic side of their relationship within the context of the Hetalia universe.
There are some out there. For example, there are fanfictions that depict Fem America getting kidnapped by Pirate England and then an unexpected bond forms between them during her captivity. Another type might be where they team up against a common enemy at sea. You really have to dig around a bit to find the best ones, but they do exist.
Chapter 525, "Barely Winning", is the clearest early answer because it turns Damien's situation into a concrete plot event. The setup is The captain retaliated with a knee to Damien's abdomen., but the pressure keeps building through Damien vomited blood on impact but the demon didn't stop..
Chapter 116, "Great Righteousness, Hunting Flood Dragons, Saliva [Five-in-One Mega Chapter]", is the clearest early answer because it turns Zhao Long's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Luo Yuan, Zhao Long, and their two other brothers, along with Yuan... and follows through with The trunk of that tree had a diameter of about eight meters, not the....
Chapter 511, "Dreams For After School", is the clearest early answer because it turns Daveon's situation into a concrete plot event. The setup is The training grounds of ElderGlow Academy rang with the sharp crack..., but the pressure keeps building through Morning sunlight filtered through the tall crystalline pillars that....
Chapter 401, "Ruins On Their Way To Delwig", is the clearest early answer because it turns Damien's situation into a concrete plot event. The setup is The stench was the first thing that hit them., but the pressure keeps building through Acrid, metallic, and bitter, carried on the drifting wind like the.... Once the chapter lands on Their lives weren't taken—they were harvested." Lyone stumbled back,..., the chapter closes with Once again, thank you all for sticking around this far.
Chapter 9, "Ice Shuo, Vermilion Frost, Gold Lin", is the clearest early answer because it turns Red Frost Tree's situation into a concrete plot event. Early on, The Great Xia Camp has finally birthed a new logging-grade combat.... By the end, The inner trees were more terrifying, with diameters of five or six....
Chapter 512, "Just A Little More", is the clearest early answer because it turns Damien's situation into a concrete plot event. The setup is The Forest of Twin Disasters did not rest., but the pressure keeps building through While others trained within reinforced walls and dreamed of futures....
Chapter 123, "Arrow Bamboo Forest, Rat King, New Camp", is the clearest early answer because the buildup finally cashes out in a real clash. The chapter turns that into something concrete by moving from Looking at the Rat King's skinny, pointed face still full of fierce... to The more than two hundred rodents that had just burrowed into the....
Chapter 533, "Go To Hell", is the clearest early answer because it turns Fenrir's situation into a concrete plot event. The chapter gives readers a real answer by opening on For a moment after Damien spoke, the forest held its breath. and ending on Why was he letting his beasts, something moved beside it.. In story terms, the chapter closes with And somewhere far away...
Chapter 503, "Sleep In Peace I", is the clearest early answer because it turns Damien's situation into a concrete plot event. The chapter turns that into something concrete by moving from Jaws opened wide, lined with rows of jagged teeth dripping with... to This time, Damien skidded backward several meters, boots carving.... What makes it stick is that the chapter closes with "Fine," he said quietly.
Chapter 533, "Go To Hell", is the clearest early answer because it turns Fenrir's situation into a concrete plot event. The setup is For a moment after Damien spoke, the forest held its breath., but the pressure keeps building through The valley had gone unnaturally still.. Once the chapter lands on Why was he letting his beasts, something moved beside it., the chapter closes with And somewhere far away...