Migrating angular-toastr / toastr to modern Angular

angular-toastr showed success, error and warning toasts from anywhere through an injected service.

What replaces it

Option	When to choose it
ngx-toastr	Same concept and options; the quickest swap.
MatSnackBar	When you use Angular Material.
Your own service with CDK Overlay	When notifications are part of your design system.

Wrap notifications in your own NotificationService so components never call the library directly.
Downgrade that service and switch the legacy code to it.
Swap the implementation underneath once, for both frameworks.

Watch out. This is a good first migration: small, visible and low risk. It also proves that a downgraded service works in your hybrid setup.

In a 20-minute call you describe your situation and I tell you how I'd approach it. If it isn't worth doing yet, I'll say so.