is extremelly popular in the US for chatting, much more than WhatsApp actually. However, there is no way to add this option.
As a business, I own a business iMessage account. I just need to allow my visitor to click on Help
As a result, you only need to add the option, the icon, and let me paste the URL.
Apple iMessage is native to macOS. So native that when you click on the URL above it opens macOS iMessage directly by default without showing any browser window.
Folks, our former Wishlist portal, where our users shared their requests and suggestions, was transferred to this forum. You’re most welcome to vote, add new ideas, and leave your comments here — we surely will consider them all! 
Original Votes: 1
Hello Stan,
Thanks a lot for submitting this idea!
We understand how useful Apple iMessage option would be, so we will try our best to consider its implementation in the nearest updates.
We do appreciate your help in our widgets improvement, and if you come up with any additional ideas, please don’t hesitate to let us know in the comments here.
Thank you!