This app was mentioned in 7 comments, with an average of 1.43 upvotes
The app Type and Speak can serve as a text to speech device. It has a neat feature that lets you save and easily replay favorite phrases, and a large font option.
I use an android phone, so take this as you will.
My phone app is called Type and Speak.
My computer app is called Talk For Me from Retcon Apps, in the Windows Store.
In the past, I have used an app called Type and Speak to do this, just use the little save icon. I currently use Tasker though.
I'm sorry I guess its been removed from F-Droid. It is still in the play store if you want you can just grab the apk or build the app from source.
https://play.google.com/store/apps/details?id=com.googamaphone.typeandspeak&hl=en
You could use Type and Speak to record a spoken custom sound for each app, then go into each app and tell it to use it's sound file.
The only thing better than reading these reviews is copy pasting them into this to be read aloud
https://play.google.com/store/apps/details?id=com.googamaphone.typeandspeak&hl=en
I'm sure ther are equivalents on apple app store if your tablet is an ipad.