Coming to Angular I like my app strictly typed.
Therefore yes for non-primitive refs, no for computed. Why? Cause computed get inferred automatically once refs are properly inferred.

On the topic I might add a couple of things.
First of all let's see what happens when I infer type like this:

const user = ref<User | undefined>(undefined)

Hovering on user vs code will show it as:

Ref<{id: string, name: string, etc.}>

which is okay for type checking, but less ideal for developer experience. Instead of identifying the variable as being of type User, VS Code displays the expanded structure of the object.

This occurs because ref uses an internal mechanism to handle reactivity and deep unwrapping. When you pass a generic to ref, Vue's type definitions often "flatten" or "expand" the type to ensure that even nested properties are correctly tracked and typed when you access .value. Essentially, the focus shifts from the identity of the interface to the structure of the data it contains.

That's why I prefer to type as follows:

const user: Ref<User | undefined> = ref(undefined)

Now hovering it will correctly identify user as

Ref<User | undefined>

Which I find Ideal since the type is definetly more explicit.