I haven’t used Sparkle myself so I may be a bit off, but as far as I can see Sparkle requires you to constantly update an xml file so it knows what to update. Pakkly allows you to specify a glob to search for in the releases area. So you can simply target myapp_mac_*.zip and your users will automatically be updated when they next start the app. Notarization is a process I’m planning to integrate via a CLI, if possible.

Also, it’s cross platform, if you ever decide to branch out :)