You have two Microsoft 365 tenants. Users have accounts in both tenants.
You plan to deploy a single device to each user. Each device will contain the Microsoft Authenticator app.
You need to ensure that the users can use their device to authenticate to both tenants by using passwordless authentication.
Which platform should you provide?
To ensure users can use a single device to authenticate to both tenants using passwordless authentication, you should provide an iOS platform. The Microsoft Authenticator app supports passwordless authentication for multiple accounts on iOS devices, allowing seamless switching and signing in to different accounts from the same device.
Answer correct https://learn.microsoft.com/en-us/entra/identity/authentication/howto-authentication-passwordless-phone
You can enable passwordless phone sign-in for multiple accounts in Microsoft Authenticator on any supported Android or iOS device this Q is obsolete
You can enable passwordless phone sign-in for multiple accounts in Microsoft Authenticator on any supported iOS device. Consultants, students, and others with multiple accounts in Microsoft Entra ID can add each account to Microsoft Authenticator and use passwordless phone sign-in for all of them from the same iOS device.
https://learn.microsoft.com/en-us/entra/identity/authentication/howto-authentication-passwordless-phone