what exactly is content syndication?

Let your version get indexed before the copy goes up anywhere else. Give it a few days and check it shows in Search Console. If the partner publishes the same morning and they're the bigger site, Google can easily treat theirs as the original - a canonical is a hint, not an order. Google's own guidance now leans towards asking the partner to noindex their copy, which is the safer ask if they'll agree to it.

Republishing something you have already published, somewhere that is not your site - a partner, a trade publication, one of the big platforms. The point of it is reach: you are borrowing an audience you have not built yet. The thing to get right is that their copy should point back at yours as the original, ideally with a canonical tag and at minimum a visible line saying where it first appeared. Otherwise you have handed them a page that competes with your own for the same query. At a small scale I would do it when somebody asks, rather than building a programme around it.