Retro, the friend-focused photo-sharing app built by former Instagram product engineers Nathan Sharp and Ryan Olson, has raised north of $21 million in Series A funding, according to an SEC filing. The fundraise is a testament to the enduring need for social apps that connect people with one another more directly, instead of through personalized algorithms filled with creator content, and now, often, AI slop. “Something that has to be true and will be true is that people will still want to see more of their friends,” Sharp told TechCrunch in December, referring to how For You-style feeds have taken over today’s social media. “The photos and videos you take will need to find a place where they can reach the intended audience,” he said. Business Insider first spotted the SEC filing, which is under the startup’s name, Lone Palm Labs. The filing, dated August 19, indicates the funding itself was closed in December. Pitchbook now estimates the startup is valued at over $100 million. Retro didn’t immediately respond to a request for comment. Launched in …