netlify-identity-widget | A zero config , framework free Netlify Identity widget

What did you try so far? As @ksav pointed out, in this GitHub thread there are a several ways to fix a similar issue:

• Removing node_modules, .cache and install again
• Removing node_modules, .cache fix Gatsby to v2.23.3/upgrade up to ^2.26.1 where the bug is fixed and install again

It seems related to a loading staticQuery bug that can't be reproduced in a fresh install. The final trial is to remove your package-lock/yarn-lock.json and generate it again.

Exactly, what happens when we "alias" the React Native to Web?

It means the library react-native-web will convert the react-native components into HTML/CSS tags.

Here an example:

I'm an awesome text

Will become into when rendered on browser:

When working with Expo, why isn't some packages available? For example, the LinearGradient get's an error saying it can't be found.

Expo offers a very simple way to start developing React Native apps. But it's a closed box where you cannot add community native packages, only the native packages that comes with Expo. There is an exception, the js-only packages, like: https://github.com/crazycodeboy/react-native-check-box

For the native packages, you need to link them in the native side of your app and compile it. To achieve this I suggest you to start in the native development, you can found the path here: https://facebook.github.io/react-native/docs/getting-started#the-react-native-cli

I want to use Netlify Identity Widget, but that renders in HTML. How do I use that with React Native Web?

You can use any package/widget/library that renders HTML, because you will run it on browsers. You can start using it just typing yarn add netlify-identity-widget or npm install netlify-identity-widget --save into your react-native-web root folder.

Hope I helped!

Not sure if this will help, but I had the same issue as this and realized I had a package-lock.json and a yarn.lock file. I deleted my yarn.lock file and it fixed the error.