Is this currently an existing feature request?
No
Wishlist item
Custom Extensions for Wix Blocks
What current pain point are you facing?
I am building a app which needs to handle additional fees. If I try to implement it with the SPIs my server endpoint does not get called. It would be much easier if custom extensions would be as easy to implement in blocks as in the normal editor.
Do you have a current workaround that you’re using?
I add custom products to the store and the cart. This is not functional because the custom products are shown in the store and can not be hidden.
Describe the feature you need and how it would work. (Bonus points for mockups 
)
Custom extension feature just like in the wix editor.
How will this impact you?
I will be able to implement my additional fees app much quicker and do not need to use my server for this.
Thank you Wix-Team! Wix is a really great product. I think more third-party apps would help strengthen Wix’ position for example against shopify.