We don't know any good Buttonizer Pro open-source alternatives yet.
You are more than welcome to suggest any alternatives that you know of, or ask the community for suggestions.
Alternatively, we recommend checking out LibHunt for open-source libraries and alternatives to Buttonizer Pro.
With over 40+ button actions, Buttonizer is the most versatile Smart Floating Action Button & widgets application. Great for floating chat widgets, WhatsApp widgets, contact forms & more.