I have made almost same looking widget by using https://pub.dev/packages/flutter_dash, you can also customise this widget according to your style.
Here is the code,Hope it helps.
Column(children: <Widget>[
Container(
margin: EdgeInsets.only(top: 16),
height: 25,
width: 25,
decoration: BoxDecoration(
shape: BoxShape.circle,
border:
Border.all(width: 1.5, color: Colors.greenAccent)),
),
Dash(
direction: Axis.vertical,
length: 130,
dashLength: 15,
dashColor: grey),
Container(
height: 25,
width: 25,
decoration: BoxDecoration(
shape: BoxShape.rectangle,
border: Border.all(width: 2, color: red)),
child: Container(
height: 20,
),
),
],
),