So, we've now or will soon have:

Mac TTS voices on Windows.
Mac TTS voices on Linux.
Mac TTS voices that were first made for computers, on Android.
Google TTS voices on Windows.
Keynote Gold on just about everything. IDK if they's one for Android or iOS yet though but like if y'all need it I can ask the machine god to make it. Come on Omnissiah, reset my five hour limit!
Eloquence (IBM TTS) made natively for everything. Well okay it will be soon I'm sure. Then I can make it talk Southern. Lol.
DoubleTalk, Monolog, Echo, and a lot of neural voice engines like Pocket TTS. That'd probably work well on an iPhone actually, with its ML chip, and high end Androids too.

I mean, I've honestly got all the TTS I want now. Now we just need, um, animated? soundscapes that change based on what you're doing. Could keep me awake on days when I'm bored. And little digital fidget toys we can play with like those little pet things you play with with your mouse. Oh no y'all stop me from coming up with more ideas.