With one armed biking, giving proper bike turn signals is usually not possible.
The trick therefore consists in a technical solution to indicate turns.
The product was bought on Aliexpress.
Overall bike setup as of now: rack with bag, and a provisional (not perfected yet) handlebar light.
My double cable brake lever and the two Silver shifters that I used to put the down tube shifters on the handlebar.
Also I put on new brakes : )
So far, so good.