The Lookup component is missing a readonly state even though it uses a text input under the hood. The readonly state should not only match TextInput, ChipInput, etc but also prevent users from interacting with the menu or menu items.

Technical notes:

In T382340#10409415, @AnneT wrote:

Noting here that readonly styles and input behavior currently exist in Lookup because the readonly attribute gets passed to the internal TextInput. However, if there are menu items (such as the case of initial suggestions), the menu will open and be accessible even in the readonly state.