Vue library typings

I'm making a Vue library as an NPM package which is intented to be used by other projects.

The entry point is main.ts, which exposes a plugin and some functions that I commonly use. A simplified example of main.ts:

import Vue from 'vue'
import Button from '@/components/button.vue'

const myPlugin = {
  install (vue: typeof Vue): void {
    vue.component('the-button', Button)
  }
}

function someFunction(a: number, b: number) {
  return a + b
}

export { myPlugin, someFunction }

I build the project using vue-cli-service build --target lib --name myLibrary src/main.ts.

Now to my question; how to specify and/or generate typings correctly? As far as I can see, there are two options:

1. Set "typings": "src/main.ts" in my package.json and use the .ts files themselves as type references. Seems to work but I haven't seen any examples of this being used so I assume it's bad practice?

2. Set "declaration": true and "outDir": "types" in my .tsconfig.json. Along with some tweaking in vue.config.js typings seems to be generated correctly, which I would specify with "typings": "types/main.d.ts" in the package.json file. Is this the preferred approach?