That literally wouldn’t work on Android, or ios. And android’s solution is very elegant, and only relies on standard linux interfaces, so there is zero reason why running every process under a new, dynamic user is not the default way of interaction.
That's what power users do when say 'Linux in insecure because wih $HOME you can loss all you real life assets'. Wel, first at all, anyone with at least two neurons would create separate users for work, financial/goverment data and gaming/leisure/casual browsing.
That literally wouldn’t work on Android, or ios. And android’s solution is very elegant, and only relies on standard linux interfaces, so there is zero reason why running every process under a new, dynamic user is not the default way of interaction.