Fanfiction.net is another option. It has been around for a long time and has a wide variety of fan-created stories. You might need to do a bit more digging to find the exact 'Harry Potter' and 'Peter Pevensie' fanfiction you're looking for, but it's definitely worth exploring. Just use the search bar and type in relevant keywords.
Websites like Archive of Our Own (AO3) are great places to start. It has a large collection of fanfiction, and you can easily search for 'Harry Potter' and 'Peter Pevensie' crossovers. There are filters to help you find the most popular or recently updated ones.
Some dedicated Harry Potter or Narnia fan forums may also have links to or discussions about such fanfiction. For example, the Leaky Cauldron forum for Harry Potter fans might have some threads where fans share their favorite crossovers involving Peter Pevensie. You can join these forums and ask for recommendations as well.
Chapter 871, "Emergency Incident", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter turns that into something concrete by moving from He really didn't expect such a coincidental event to happen to him.
Chapter 598, "She Blew Up Your Family's Lake!", is the clearest early answer because it turns Miss Jiang's situation into a concrete plot event. Early on, Have you all fallen silent?] [I've fallen silent as well.] [Some say....
Chapter 894, "I Want to Attend the Same University as My Sister", is the clearest early answer because it turns Want's situation into a concrete plot event. The chapter turns that into something concrete by moving from The sound of early summer cicadas was close to the ear.
Chapter 457, ""Back Against the Wall", is the clearest early answer because it turns Mr's situation into a concrete plot event. It opens with Five minutes later, he stared at Yu Li with his twitching mouth... and closes on How could he know what this mad fortune-teller was up to?.
Chapter 576, "The Electronic Pickles are Gone!", is the clearest early answer because it turns Team's situation into a concrete plot event. The chapter turns that into something concrete by moving from Tonight, Team Q exceptionally didn't cook.
Chapter 546, "Good Sister, Stop Hitting Me, I Was Wrong!", is the clearest early answer because it turns Was Wrong's situation into a concrete plot event. The chapter gives readers a real answer by opening on Jiang Li squinted her eyes, her expression colder than ever.
Chapter 785, "Signing with Taiqi", is the clearest early answer because it turns Jiang Shixu's situation into a concrete plot event.
Chapter 621, "What Makes You Think I Would Save You?", is the clearest early answer because it turns Su Yinwan's situation into a concrete plot event. The chapter gives readers a real answer by opening on The two walked for a long time before they reached a point where the...
Chapter 801, "This Elder Sister Is So Smart", is the clearest early answer because it turns Jiang Zhao Yuan's situation into a concrete plot event. The chapter turns that into something concrete by moving from Buchen is quite diligent, he even knows how to tidy up his own...
Chapter 855, "This is Made of Gold!", is the clearest early answer because it turns Buchen's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Sure enough, kids with sweet mouths get candy.