- "Toronto employment lawyer Lior Samfiru told Go Public that employers can compel employees to download an app on their cell phone — but only if they're told it's a requirement when they are hired."
So it's legal. Moreover, the lawyer continues saying that an employer can fire someone for any reason. So, if you don't sign an addendum with app requirement and install the app on your personal phone, then you are fired.
[1] https://system76.com/desktops/thelio-astra-a1.1-n1/configure