Hi @AOZ
I believe it is possible to use the attachment images. I also agree that the Shane Young Video is good. @RezaDorrani has a good one too https://www.youtube.com/watch?v=Da4do2DxmJE.
I have tried the following:
Retrieve the attachments from the list Item (using the Item ID), then in an apply to each, I get the file content of each file and output to a compose.

Outside of the Apply to Each, I then use "Pieters Method" to bring together an array of the file contents using a compose.

A select is used to create an array of HTML IMG tags using the DataURI expression.
I join the array using a select action with BR tags to insert some break lines between images (html formatting of your choice at this point ! 😉 )
A compose to insert the img html into the main HTML
And then finally a create file action to create the HTML file.
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.
Cheers,
Damien
P.S. take a look at my new blog here and like & subscribe to my YouTube Channel thanks 😉