Are you suggesting they will draft the law in such a way that in order not to be fired people must download this thing onto a smartphone and show it to their employer, post-haste? Your link does not support any evidence of that (the line " will be mandatory for every worker in the UK" links to just another one of their own articles, which also does not support it). I imagine it'll be phased in for new employment.

No, it won't be mandatory in all situations all at once, for every facet of life (I did not specify employment).