Hi Nikos, I talked with a SEO specialits about it. You own this content. All you have to tell Google is which one is the original source.

Re the video suggestion: do you mean how to repurpose your MEdium stories on Substack?

I repurposed about 5 I think. I prefer original content but promoting Medium via Sub and Sub via Medium.

Here's more: https://youtu.be/RBv4cTnv_tw?si=AswLGO8Mktv4q36e