It's not explicit enough for dummies like me, but the Safari extensions gallery is the Safari browser extension app store equivalent (available in browser) and

It's not explicit enough for dummies like me, but the Safari extensions gallery is the Safari browser extension app store equivalent (available in browser) and one can submit the app and include the extension for publication in the app store and the extension gallery at the same time it appears (haven't tried or gotten that far yet). "You can sell and distribute your apps with Safari Extensions to customers worldwide on the Mac App Store. To submit, sign in to App Store Connect. For information on creating Safari Extensions for the Mac App Store, see the Safari App Extension Programming Guide."