Images per deep links?

I use Obsidian on 4 devices (MacBook, iPad, smartphone and Win-PC) and would like to reduce storage space - especially for the smartphone.
I think it’s a good idea to save images that I include in Obsidian texts not in the local directory, but in a NextCloud.
For this to happen, something like deep links should be possible with Markdown path information.
Does anyone know if and how?