I live in Switzerland
I follow the instructions in force of the Federal Office of Public Health (FOPH).
If the person returning from a State or territory at high risk of infection (see the FOPH List) resides/stays in Switzerland, they must immediately go into self-quarantine for a period of ten days. They must, within 48 hours, declare their arrival to the competent health authorities of the canton in which they reside, or for a traveller, the canton in which they will be staying.
In Geneva, the declaration is made to the cantonal doctor’s office via an electronic form. After one or two days, recommendations and explanations are sent to the person concerned by e-mail. They will also receive an official quarantine decision.
If the person resides in France, they are not currently subject to this quarantine obligation. They will pass through Genève Aéroport, both international and French sectors, without any particular control to reach their place of residence in France.
Passengers who have stayed less than 24 hours in a State or territory at high risk of infection are not required to self-quarantine.
I live in France
I follow the instructions in force on the France Diplomatie website.