Hi @ursus,
If you’ve already calculated the point locations then you could draw the vertical bars using bar traces (https://plot.ly/python/bar-charts/) underneath the scatter trace holding the points.
To match the aesthetic of your example, set the layout.bargap to something like 0.8 (0 is no gap between and 1 is a bar width of zero), and set the bar.marker.color to the same color as the scatter markers but set the bar.marker.opacity to something like 0.6.
Hope that helps!
-Jon