This is unnecessary
Always-on culture occurs when people can't switch off from their work.
Not really, it occurs when people won't switch off from their work. Learn to say No.
France adopted a right-to-disconnect law (L2242-17.7) in 2016.
And a right PITA it is too. I work with teams in the US, EMEA and Australia. It is really convenient for me to have meetings and respond to emails when I want to. I can choose to reply at 10pm, or on a Sunday, if I want, knowing that it will avoid something spiralling into a crisis by my next official work period. I can also look out the window at the fresh snow when I get up, decide to ignore my phone and go skiing for the morning & then shift my day to align better with the US folks. Works better for everyone. If HR knew they would order me not to, and so make my work more difficult, but fortunately it's France, where everyone ignores inconvenient laws.