Start listing action items according to the priority, so you perform all the tests and cover all the necessary testing areas.
Automation is the key to speed! Select automation testing tools to gap the issues faster.
Start using real assertive technologies such as screen readers, magnifiers, and switch controls to test the app. Consider all use cases according to users to deliver the best.
Ensure your app is accessible to all users with different languages; better compatibility will lead to a vast reach.
Get access to different devices, operating systems, and screen sizes devices pool. Either build it in-house or use a platform that gives access to it.
Take help from people with disability; they can provide valuable feedback and help you identify issues that you may have missed.
Test your app with different color filters to ensure that the app is accessible for users with color vision deficiencies.