You could potentially base64 encode the image? So if the image is a link to a src like: "url/picture.png" download the image and the base 64 encode it into a string then repleace the src with the encoded string.
So you would need to create an on change or on the save microflow button that would find all tags and replace the src=" " part with something like:
So convert
<img src="image location"></img>
to something like:
<img src="data:image/gif;base64,R0lGODlhEAAOALMAAOazToeHh0tLS/7LZv/0jvb29t/f3//Ub/
/ge8WSLf/rhf/3kdbW1mxsbP//mf///yH5BAAAAAAALAAAAAAQAA4AAARe8L1Ekyky67QZ1hLnjM5UUde0ECwLJoExKcpp
V0aCcGCmTIHEIUEqjgaORCMxIC6e0CcguWw6aFjsVMkkIr7g77ZKPJjPZqIyd7sJAgVGoEGv2xsBxqNgYPj/gAwXEQA7"
width="16" height="14" alt="embedded folder icon"></img>