No support Apple Safari?

[bengarrett]

But only offer a GitHub package download due to the App Store $99 requirement?

Safari 14 ships with iOS 14 and macOS 11.

Right now it requires Safari 14 on a seed build for macOS Big Sur but will be backported to Mojave and Catalina.

Added Safari Web Extensions support for macOS.

https://developer.apple.com/documentation/safariservices/safari_web_extensions

Assessing Your Safari Web Extension’s Browser Compatibility

Note:

Safari web extensions are implemented as macOS app extensions to provide a safe and secure distribution and usage model. You must use Xcode to package your extensions for testing in Safari, and you must be a member of the Apple Developer Program to distribute them through the App Store. For more information, see Apple Developer Program.

---

Reasons not to.

The cost is $99 USD per membership year to distribute on the Apple platform.
You must use Xcode to package your extensions for testing in Safari.
No iPadOS support. Support added to iOS 15.