Earlier quoted context omitted.
You might give Larynx a try: https://github.com/rhasspy/larynx Demo: https://youtu.be/hBmhDf8cl0k (I'm the author)
Wow. I'd really encourage you to invest some time into SEO and promotion of your project. I spent a bunch of time recently looking for exactly this: TTS, offline, an Open Source licence, and with "decent"/"natural" sounding default voices. The "best" I ended up finding was `espeak-ng` but, really, the "natural"-ness is barely comparable to what Larynx seems to produce--based on a quick listen to the demos here: https…
While I appreciate the cinematic aspect of the confirmation/"reveal" at the conclusion of the video, ironically--because the quality is so good--since most people won't get through a 7 minute video, it would be entirely possible to not realise the narration itself is generated.
So I'd encourage you to consider stating it a little more up front.
(Also, based on the release dates it seems like this project is relatively young which explains why it's not very well known at this point.)