HI,
Super Simple
Steps
1. Create a Solution
2. Add a New Flow to your solution.
-Create an Instanct Flow
-Select the Power Apps V2 Trigger
2. Add whatever Steps you want to do in the Flow
Now this Flow is part of your Solution and your App will see it
3. Create Your Canvas App in the same Solution
Add your Button
Once the App is Open, you need to click the Flow Tab on the Left Side
4. Select the Flow
I don't have any to add as I already added them
but you would see your new flow there
5. Once your Flow is added, you can now call it from the Button
Here is my OnSelect, where I am calling flows I already have connected
['[Sample]SendAttachmenttoFlow'.Run("MySingleParameterValue")]
So now I have called my Instant Flow from a button in my Canvas App
My flow asked for a single parameter, you can add whatever you want, even JSON
And answered