Importing multiple JSON files int PBI (Data Source = Admin API GetDatasourcesAsAdmin)

Here is a way to check for record vs. list as part of your parsing. As stated previously, you can simply wrap the records you find into a list and then treat all outputs the same.

let

    Source = Folder.Files("<local file location with your json examples saved>"),

    //parse the json, if a single record, wrap in list so they are all list of records
    ParseJson = 
    List.Transform( 
        Source[Content] , //binaries are in "Content" column
        each let 
            json = Json.Document( _ ), 
            valTypeIsRecord = Type.Is( Value.Type( json ), type record ) 
        in
            if valTypeIsRecord //if it's a record
            then { json } //wrap in a list
            else json //otherwise leave as is
    ),

    //list of list of records --> list of records
    CombineRecords = List.Combine( ParseJson ), 

    //uniform transformation - Table.FromRecords is designed for list of records
    ToTable = 
    Table.FromRecords( 
        CombineRecords, 
        //provide exact types here so we don't have to later
        type table [
            datasourceType=text,
            connectionDetails=[server=text,database=text],
            datasourceId=text,
            gatewayId=text
        ] 
    ),

    ExpandConnectionDetails = 
    Table.ExpandRecordColumn(
        ToTable, 
        "connectionDetails", 
        {"server", "database"}, 
        {"connectionDetails.server", "connectionDetails.database"}
    )

in
    ExpandConnectionDetails

Pics of steps so you can see better what's going on: