I have the following package my library having a class an interface exported.

src/Notification.ts

import {INotification} from 'INotification';

export class Notification implements INotification {
    private readonly _name: string;
    private _body?: any;

    public constructor(name: string, body?: any) {
        this._name = name;
        this._body = body;
    }

    public get name(): string {
        return this._name;
    }

    public get body(): any {
        return this._body;
    }
}

src/INotification

export interface INotification {
    readonly name: string;
    body?: any;
}

index.ts

export {Notification} from './src/Notification';
export type {INotification} from "./src/interfaces/INotification";

Project using my library

I manually copied mylibrary into node_modules folder

package.json

"dependencies": {
  "react": "18.2.0",
  "react-native": "0.71.19",
  "mylibrary": "file:node_modules/mylibrary"
},

App.js

import {StyleSheet, Text, View} from 'react-native';
import React from 'react';
import {Notification} from 'my library';

const App = () => {
  const n = new Notification('a', null);

  return (
    <View>
      <Text>{n.name}</Text>
    </View>
  );
};

export default App;