heyo! so it will show the Whenish thumbnail in the chat when it is sent. when the user without Whenish clicks on it they will be routed to the app store to download Whenish.

I get it, but that's a hurdle for a lot of people. If someone is using this just once, they don't want to download an app. This feels like it will take convincing.

Perhaps, but if one person in an iMessages thread has it installed, that user’s recommendation will go far towards installing.

oic. maybe add an ascii poll display until it's installed?