All forms of authentication I have found requires interactive login. An Azure Managed Identity does not have any such thing. Simply the ability to manage resources... So how does on get the managed identity to be acceped by bit bucket and the appropriate tokens put in:
{
"id": null,
"name": "Bitbucket",
"type": "Microsoft.Web/sourcecontrols",
"properties": {
"name": "Bitbucket",
"token": "Not-My-Real-Token",
"tokenSecret": null,
"refreshToken": "Not-My-Real-Refresh",
"expirationTime": "2021-10-27T17:00:30.7994446Z",
"environment": "Prod"
}