You are a PM at Google. Design a feature for a product meant for a completely blind person.

Sure, it feels good to be here at Google :)
Clarifying questions
- Which product of Google do you want me to target?
- How do you define blind- Completely/partially + By birth/by some illness
- Is there any other platform that does something like this?
- What is the goal of Google behind this?
- Is there a specific preference to which platform I should target them, like software/hardware etc.? google.com, software search>
- Will it be directly served to the user or via some organization/community who are helping them?

Getting into the shoes of the user.
Since the user is blind due to some illness, I will take the user to be in the age group~ 10-60, an age group that can be taught to use a new but simple tech product easily.

Since you mentioned software, I will assume the user is using at least a network based gadget, and considering blind, it will a mobile phone(that too a feature phone).

For the sake of the interview, I will consider that the user will not depend on anyone for using this. 
So, a blind person might need google search for-
- Entertainment- Songs, etc.
- Information/Education purposes- Podcasts etc. 
(Not considering any actions because you mentioned focusing on google.com search earlier)
- Currently, they depend on their caretakers for this.
- Senses through which they interact- Sounds, Touch, (Smell, Taste.ignored)
Refined goal- Removing the dependant from the scene.

The product!
4 possibilities- Input= Sound/Touch, Output= Sound/Touch
Output as touch will be costly, may affect user acquisition.

Touch as input- More accurate, a bit habituated, but time taking

Sound as input- Less accurate, easier, quick.
Taking into consideration the success of Google Assistant- I'll go with sound because typing even a word takes long on T9.

Sound Input -> Result -> Sound Output

Increasing the ease and interaction

Sound Input -> Feedback-> Result -> Sound Output

Increasing controls

Sound Input -> Feedback-> Result -> Sound Output -> Feedback for navigation/more results->Sound Input ->.......

Activation- Taking into mind, feature phones- Always-on-mic will be difficult, will configure "long press a button to open" option.

Long Press -> Sound Input -> Feedback-> Result -> Sound Output -> Feedback for navigation/more results->Sound Input ->.......

Connectivity- Internet vs call. Call- costly, but doesn't require good internet, Internet- no cost issues, but requires internet. Taking into account that we have a feature phone, and speed dial can opt, I'll go with Call. + for future Numpad keys can be used and different calling numbers for different types of search ex- news, audio, etc..

Long Press to call -> Sound Input -> Feedback-> Result -> Sound Output -> Feedback for navigation/more results->Sound Input ->.......

Going deeper into the results- Only with clear titles/audio for an easier experience, read titles only and let the user chose if they want in, if yes, read the whole article/play the sound.

That's it

Feedbacks please :)