When importing stytch using nodenext typescript isn't able to find the typings.

Could not find a declaration file for module 'stytch'. 'stytch/module.mjs' implicitly has an 'any' type.
  Try `npm i --save-dev @types/stytch` if it exists or add a new declaration (.d.ts) file containing `declare module 'stytch';`ts(7016)

You should just need to add the "types" field to your exports in package.json:

  "exports": {
    "require": "./dist/index.js",
    "import": "./dist/index.mjs",
    "types": "./types/lib/index.d.ts"
  },

Ideally, more types would be exported (User, Session, etc) like #118 mentions but that can be worked around.