Help ( India )..

Just received my nothing phone 3a pro today ....Grey one .....

1. please suggest a good transparent back cover which doesn't turn yellow easily on Flipkart / Amazon /any other app which delivers in India

2. should I even use a glass over their already provided thin screen ? I had been using a OnePlus Nord CE 2 lite 5g for last 3 years and never put a new glass on it, although it has some scratches now .....if I should then suggest whether I should order and do it at home by ordering a glass online or go to a nearest phone repair shop