I appreciate this question was asked nearly two and a half years ago - but it came up in a Google search when I was looking to do the same thing.
Although the in-built "Create sharing link for a file or folder" SharePoint action still doesn't support adding a password to "Anyone" links, you can instead create such a link (and more!) using the "Send an HTTP request to SharePoint" action. This essentially opens up the wider SharePoint API to be consumed in the Power Platform.
Here's the endpoint/URL to POST to
_api/web/Lists('YourLibraryGUID')/GetItemById('YourItemID')/ShareLink
Here's the request body
{
"request":{
"createLink":true,
"settings":{
"allowAnonymousAccess":true,
"linkKind":6,
"role":1,
"restrictShareMembership":false,
"updatePassword":true,
"password":"YourPassword",
"scope":0
}
}
}
Use your browser's developer tools to see what requests the browser sends when you click the UI in SharePoint - from there you can figure out the API (as well as Googling it!).