working in vs2022
loads the DB names into an array
uses some kind of ADO, I think
It may also work with ADO.NET

Uses showdatabases command to the server

I found no good examples on the web, so here is a working one

Code:
    Private Sub COMBOBOXLOAD()

        On Error GoTo errhandler

        'connect and load combobox with database names

        'construct a connection string from listed text in the boxes
        'leave it here this will be overwriten??
        provider1 = "Provider=" & _Text1_0.Text & ";"
        driver1 = "DRIVER=" & _Text1_1.Text & ";"
        host1 = "SERVER=" & _Text1_2.Text & ";"
        dbname1 = "DATABASE=" & Combo1.Text & ";"
        user1 = "UID=" & _Text1_4.Text & ";"
        pass1 = "PASSWORD=" & _Text1_5.Text & ";"
        port1 = "PORT=" & _Text1_6.Text & ";"
        opt1 = "Option=" & _Text1_7.Text & ";"

        frmlogonConnectstring = provider1 & driver1 & dbname1 & host1 & user1 & pass1 & port1 & opt1

        Dim Con1 As New ADODB.Connection
        Con1.ConnectionString = frmlogonConnectstring
        Con1.Open()
        Combo1.Items.Clear()

        Dim values As Object, trs As Object
        'Con1.Execute("use information_schema")
        'Dim sql As String = "select distinct table_schema from information_schema.tables"
        Dim sql As String = "show databases"
        trs = Con1.Execute(sql)

        ' Load the values into a variant object array.
        values = trs.GetRows
        trs.Close()
        '? values(0, 1) "bigdb"
        '? values(0, 7) "testspecialchars"
        Dim numcols As Short = UBound(values, 1)
        Dim numrows As Short = UBound(values, 2)
        Xx = 1
        Do Until Xx > numrows
            'exclude server configuration db names from loading into a combobox
            If values(0, Xx) <> "mysql" And values(0, Xx) <> "test" And values(0, Xx) <> "information_schema" And values(0, Xx) <> "sys" And values(0, Xx) <> "performance_schema" Then
                Combo1.Items.Add(values(0, Xx))
            End If
            Xx = Xx + 1
        Loop

        Con1.Close()
        ToolStripStatusLabel1.Text = _Text1_2.Text & " Server Connected Successfully"
        ToolStripStatusLabel1.ForeColor = Color.Green
        Exit Sub
ErrHandler:

        ToolStripStatusLabel1.Text = _Text1_2.Text & " Server Not Connected"
        ToolStripStatusLabel1.ForeColor = Color.Red
        'con could not open
        MsgBox(Err.Description & vbCrLf & vbCrLf & "Check connection settings")


    End Sub