To enable Firefox Web Push notifications for your HTTPS website, follow the Web Push SDK 3.0 Guide
Firefox Web Push Notifications allow you to address the audience of your website. Users will only receive messages from sites for which they have granted permission.
Firefox Web Push Notifications are not allowed for mobile devices yet, but Mozilla is reportedly working on it. Consequently Firefox will support mobile web pushes in next versions of their browser.
To complete Firefox configuration go back to your Pushwoosh Control Panel and select your application. Go to the Configure tab and сlick Configure.
Check "enable Firefox notifications" and click Save.
Browser push notifications are available starting from Firefox 44.
Please note that Firefox pushes require https websites;
Firefox pushes will not work with self-signed certificates (https/ssl). Use an SSL certificate signed by trusted Authority;
Push notifications don't work in "Private" mode.