Hi @Frederic, got it exactly where you describe, the Dragon Mart.
Most suction cup flag systems there are 1 cup, found this one which is basically based on one of those dual suction cup handles they use to lift window panes. Seemed quite sturdy, bought it for when I take another car out that does not have a permanent solution.
Came with a very long flag, so I didn’t put it on the window as I don’t trust that with a lot of momentum. Down on the metal bits should be fine, pic below.