I am of the opinion that buying a Pocketbook just because of TTS makes no sense.
As for TTS, I would recommend the mobile phone application: "EVIE", or "Voice Dream" if you have an iPhone.
EVIE for Android :
https://play.google.com/store/search...ps&hl=en&gl=US,
VoiceDream :
https://apps.apple.com/us/app/voice-...er/id496177674
TiP : Depending on the phone brand, it is also possible to start the function (the name may be different depending on the phone) of reading text from the screen.
Turn on Select to Speak :
https://support.google.com/accessibi.../7349565?hl=en
Just start the KINDLE application, open the book you want to read and select → read text on screen.