Migrate from Trello to Planner?

Brent Ellis  You posted this a long time ago so I'll guess you don't need this any longer, but I just needed this now and exporting from Trello to JSON is so painful, so I came up with an alternate way. Flow (now called PowerAutomate) has a Trello connector with a trigger for "when new Trello cards are created". I wrote a quick Flow with that trigger which then takes the variables from the newly-created Trello card and creates a Planner Plan task.  While this doesn't initially appear helpful for previously-created Trello boards, actually, once the Flow is set up, simply duplicate a Trello list (copy and paste) and Flow sees the 'new' (duplicate) cards and new cards and will thus recreate each card in Planner.  I got fancy and used the "List Buckets" and "Create Bucket" modules in Flow to duplicate the Trello lists of cards to the appropriate buckets in my target Planner Plan.  See below for Flow step details - mine is longer b/c I am preserving the Trello lists as Planner buckets, but in essence, this Flow only needs the Trello trigger and the bottom two 'create task' and 'edit task' modules to work.

Sadly, Flow has access to several variables from Trello cards (card title, description, due date, comments, attachments, etc.) but (disappointingly) the only things it can add to a Planner Task are title, description, bucket, and due date.  Therefore, Trello card attachments, comments, and owners cannot be added to Planner Tasks via Flow (yet).  These items may be added to the Description field in the resulting Planner task, but I’m guessing that will be very ugly and not helpful.

Hope this helps!