Subscribing to web push notifications is done through a native opt-in that is shown by the browser.
Native Subscription Method: Browser Prompt
To receive your notifications, your visitors need to allow notifications through the browser prompt. The browser prompt pops up when a visitor first comes to your online store. When the visitor clicks on 'Allow' on the browser prompt, they become your subscriber.
There are 3 types of custom opt-ins you can set up on your store.
1. Custom Prompt
The Custom Prompt is a subscription method that shows a widget at the top center of the screen. It can be customized to show copy written by you and you can use this to explain why your shoppers should subscribe to your store.
Read this guide about Custom Prompt and learn to set it up.
2. Flyout Widget
The flyout widget gives you the option to show your visitors a custom message. Unlike the browser prompt, you can encourage your visitors to subscribe with offers, discounts, and other incentives.
The flyout widget also helps in recapturing visitors who blocked notifications via the browser prompt. This ensures you don’t lose the chance to convert your returning visitors into subscribers.
Read this extensive article about flyout widgets and frequently asked questions about it.
3. Custom Buttons
By designing custom buttons which look native to your theme and brand design, you can make the opt-in experience visually appealing and seamless for your visitors. This can be done by making changes to the theme code from your Shopify dashboard.
Read this guide to add custom buttons to your online store.