GET page content with images displayed in frontend

Hello everyone,

I’m currently facing the problem, that I don’t know how to get images within a page content displayed onto an external site.
Consider the following structure:

Backend (kotlin, Spring) - requests the page content via$pageId?expand=body.export_view
then the returned json gets cut out so that the html content can be provided to the frontend.
(Of course the call contains also the authentication headers)

Frontend (Angular) - originates the call to the backend with the pageId and prints the result onto the webpage.

Textually everything works fine, I do get the content properly, but images won’t be displayed.
Checking the html I see that those images contain the static Url to the attachments in confluence (src=“”), that’s why I guess that those images get re-requested by the frontend without the proper authentication. So does anybody have an idea how to solve it? In general I only want to read the page content of a confluencePage with everything onto it. (So images/videos and so on. But to keep it simple I only started with PNGs)
I did also found similiar questions online, but none of them really helped me. There is also this endpoint according to the documentation (rest/api/content/1234/child/attachment) but I wasn’t able to find out how to proceed with this information since I want a combination of both (Get page content & get page attachments)

Hope you understand my dilemma, thank you in advance, every help is appreciated!