Man, I wish there was more official Sero x reader content out there! From what I've seen in 'My Hero Academia', Sero Hanta doesn't get as much spotlight as some of the other Class 1-A students, which is a shame because his quirk and personality are so fun. There are a few official spin-offs like 'Team-Up Mission' where he pops up, but nothing specifically focused on reader-insert scenarios. The fandom has definitely picked up the slack though—I've lost count of how many amazing fanfics and doujinshi I've devoured that explore Sero's potential in romantic or platonic reader stories. The official merch occasionally hints at his charm too, like those character books with his likes/dislikes, but it's not the same as a dedicated story.
If you're craving that kind of interaction, I'd totally recommend diving into fanworks. Some creators nail his laid-back yet supportive vibe perfectly, weaving in his tape quirk in creative ways. It's wild how a character who initially seems like comic relief can have such depth when fans get hold of him. Maybe one day Bones or Horikoshi will throw us a bone with a drama CD or anthology chapter, but until then, the community's got your back!