When you called the useAvatar hook to create AvatechDisplay canvasm, you need to import loaderPlugin in avatarLoadingProps before importing any avatar. It is needed in order to render your avatar on the canvas.

import { RivePlugin } from "https://esm.sh/@avatechai/avatars@0.4.12-next.16/rive?bundle";

const { Live2dPlugin } = await import(
  "https://esm.sh/@avatechai/avatars@0.4.12-next.16/live2d?bundle"
);

const { avatarDisplay, context, handleFirstInteractionAudio } = useAvatar({
  //...
  avatarDisplayProps: {
    loaderPlugin: [Live2dPlugin, RivePlugin],
  },
});