qgis - Merge two points of two different polygons to get one polygon at the end

I would like to join points from two different features. I already searched for plugins, but so far but didn't find one working plugin or solution for my task.

So here is a picture of 2 polygons/feautures:

I already marked 2 points and these shall be merged with the other both on the left side. So at the end I would like to have one polygon and the 4 points in the middle for sure shall be 2.

Similar questions:

Answer

1) Enable vertex snapping on the feature

2) Use the Node Tool and drag the vertexes from the right polygon to the one on the left (the snapping will allow you to place them exactly on top of each other)

3) From the Advanced Digitizing tools use the Merge Selected Features tool (note that you have to select both features first!)

EDIT:
Screenshots of the tools: