I just skip Medium due to the walled garden. Even worse than Reddit. I have never come across a link to substack… are they an even higher wall that search engines are stymied by?
I fail to get why you think putting your stuff on Medium is a good idea.
Having used the web version of Office at my job, I know I would not pay for it. It is compatible-ish, but severely lacking in features, enough so that I don’t trust it to render properly or maintain the formatting entered using the desktop app. If that is good enough then there are lots of alternatives.