Google Messenger usually refers to Google Messages, the default SMS/RCS texting app on many Android phones; it’s just for sending texts, photos, videos, and chats. It’s generally safe, but not specifically built for kids, so there’s no strong parental control or content filtering by default. Kids can still receive messages from unknown numbers or spam. From what I’ve seen, it’s fine if basic safety steps are used (blocking unknown contacts, turning off auto-downloads, and maybe supervising usage), but for younger kids, a dedicated kid-focused messaging app with parental controls is a safer option.