Ok, i will reply to my own post 
.
Ok, Velo-Ninja has found his solution.
At least i was not able to work without using (either a custom-element or an html-component) .
But at the end i don’t have first to upload the image with the upload-button to my Wix-File-Manager, just to have the possibility to preview the picture —> sorry when i tell this, but → what a bullshit? <— .
Imagine that i have a app which handles with 1000 of pictures which has a preview for the pics i am getting from my loacal PC → do i have to upload all that pics → just to be able to preview them ???
!!! NO → SURELY → NOT !!!
Why do the → UPLOAD-BUTTON <— not provide base64-Data before uploading the image file ? 
to be able to generate a image-preview ?
However, this issue was again resolved by using an HTM-Component.
Working stable & fast.
But still my question: → Is it possible to use → fs.readFileSync(PATH), or fsExtra.readFileSync(PATH); ← in my case to be able to generate the same PREVIEW-FUNCTIONALITY but avoiding the usage of an HTML-Component or Custom-Element?
Or do i have a leck of knowledge in this case?
Getting some ideas appreciated though.