Using Forge Data Management API you can list Hubs > Projects > Folders > Items > Versions. An item is essentially a file, but it can have 1+ versions, so that's why you need the specific version. This tutorial guides you on the steps.
Once you list version of an item, it should be an array under .data, each entry on the array should have something like (simplified):
{
"type":"versions",
"id":"urn:adsk.wipprod:fs.file:vf.abcd1234?version=1",
"attributes":{
"name":"fileName.rvt",
"displayName":"fileName.rvt",
...
"mimeType":"application/vnd.autodesk.r360",
"storageSize":123456,
"fileType":"rvt",
"extension":{
"type":"versions:autodesk.bim360:C4RModel",
....
"data":{
...
"projectGuid":"48da72af-3aa6-4b76-866b-c11bb3d53883",
....
"modelGuid":"e666fa30-9808-42f4-a05b-8cb8da576fe9",
....
}
}
},
....
}
Update
From the comment, on Revit desktop, you can use:
ModelPath path = doc.GetCloudModelPath();
Guid guid1 = path.GetModelGUID();
Guid guid2 = path.GetProjectGUID();