You might want to check out VITS or XTTS from Mozilla/TTS, which can run on CPUs and supports training with custom datasets. Another option is OpenVoice (if it matures further) or Voxygen (which has some offline options). For datasets, LibriTTS and Common Voice (filtered for quality) are good English sources. You can also try RHVoice—not the best quality, but flexible for CPU usage.
For community support, the TTS subreddit, GitHub discussions for Mozilla/TTS, and OpenAI TTS communities might be helpful!