This works on both iOS and macOS

Download here

Source code: https://github.com/ajayyy/SponsorBlockSafari

Prerequisite: Install Xcode

1. Either download SafariExtension.zip from the latest release or follow the build instructions for Chrome in the readme.

2. Convert the extension to a MacOS app using:

xcrun safari-web-extension-converter /path/to/extension

3. Click run in the top of Xcode

4. Configure Safari in macOS to Run Unsigned Extensions

To develop without a certificate, tell Safari to load unsigned extensions using the Develop menu. To enable the Develop menu in Safari:

• Choose Safari > Preferences.
• Select the Advanced tab.
• Check the “Show Develop menu in menu bar” option.
• Then, choose Develop > Allow Unsigned Extensions. The Allow Unsigned Extensions setting is reset when you quit Safari; set it again the next time you launch Safari.

5. Now enable the extension

• Choose Safari > Preferences.
• Select the Extensions tab. This tab shows the localized description, display name, and version number for the selected Safari App Extension. It also provides more information about the permissions claimed by the extension.
• Find your new extension in the list on the left, and enable it by selecting the checkbox.

You do not need to follow these steps to build it yourself, these are here for me or anyone else publishing to the AppStore

1. Set Bundle identifier, version number, and build number for both targets (extension one must be different)
2. Set App category in main target
3. Edit extensionBundleIdentifier to the extension package name.