Not that anyone was asking, but it turns out that unlike "tweeting" [0], "pinning" [1] is not a trademarked activity so people should feel free to "pin" to their heart's content on their self-hosted solutions.
[0] https://www.mandourlaw.com/twitter-wins-rights-tweet-tradema...
[1] https://techcrunch.com/2015/10/26/pinterest-loses-pin-tradem...