Thanks but I have the image in the app and needed to include it in a Flow that converts HTML to a PDF
After experimenting with different options, in the end the solution wasn't too complex:
Step1: Create a variable that contains the image but when assigning the image convert it to base64 as per below:
Set(gblVariable,Substitute(JSON(myImage.Image,IncludeBinaryData),"""",""))
The substitute function strips the quotation marks from the base64
Step2: Use the variable in your HTML ie: <img src'"gblVariable"'>
Step3: Convert the HTML to PDF using well publisized Flow methods
So actually once you have the image it's no more complex using Dataverse than using SharePoint or OneDrive
I found that you can use simple Dataverse Lookups when assigning the variable but more complex Lookups threw an unexplained error. Best to have the image in your app (even if it is hidden) and then assign as above
