so I'm speaking from actual finds rather than rumors.
What I found: enamel pins, acrylic stands, printed posters, sticker sheets, a softcover artbook, T‑shirts, keychains, and a handful of limited-run plushies and postcards tied to special releases or convention booths. There have also been digital exclusives like high-res wallpapers and desktop icons bundled with some preorders. A lot of the nicer pieces (like the artbook and posters) were print-on-demand or limited runs, so stock moved fast.
If you're hunting, follow the creator's official social channels for drops and look for an official store link — buying through those channels is the safest way to support the team and actually get the real thing. Personally, the enamel pin and a small poster live on my shelf now and they feel great to own.