I think I might be trying to do something not possible with a miro board.
Our use case has many of these on a single board. It is simply three fields, a path to a file at azure devops, a PAT (Personal Access Token that has permisions to read the file) a field that contains a version number. A button to save the values, and a check button, that initiates a javascript that calls a rest api to devops to pull the current file version and compare it to the value entered. I have been able to get so far as having the html show up when I click the app, but I'm not seeing an object that I can use to place this on the board. I'm not see one of the board items that I can do this in here - https://developers.miro.com/docs/miro-web-sdk-board-items-crud