I am not sure if any app provides the first functionality but yes you are right many apps provide the feature for importing reviews via CSV file.
You can check the All-in-One Shopify app AiTrillion. You can import the reviews via the CSV file.
It has Separate product reviews and store reviews and Q&A with Ai powered solutions which turn your customer content into sales by collecting and leveraging reviews and will also enhance SEO and ranking. It has a rich snippet along with the product review gallery and product review page. Generally, rich snippets have a much higher click-through rate. If the click-through rate of your snippet increases, the amount of traffic generated will then be higher. It has an in-email review form. You can entice your customers by giving them loyalty points on leaving a review which will help you to boost sales and collect more and more reviews with the help of this app. It is a fully integrated app and has many other features with support available 24*7. You can check it out. I am sure you will find it useful.
Check here about AiTrillion Reviews feature.
Hope this helps!