FINNEAS became a household name as producer and chief collaborator for his pop-sensation sister Billie Eilish. But his solo records, with their intricate construction and heartfelt songwriting, demand attention as well. Take his 2021 single “A Concert Six Months From Now,” which uses unexpected sonics and diaristic lyrics to create a tender snapshot of pandemic-era romantic life, all tangled up in guarded optimism. His other works, like the gently funky “Claudia” and the swirling “Break My Heart Again,” are similarly rich with musical and emotional detail, and demonstrate how his take on alt-pop is ready to command the spotlight.