Firefox/Chromium Desktop
You may want to check this excellent extension out for text to speech on the web.
Windows
Your only good option is to use Dragon, I recommend just buying the local version. It is much better. It can do both transcription and dictation.
The best option for TTS is just to use the browser extension listed above.
MacOS
Use a text editor and the built in OS features. TTS STT
If you want to transcribe an audio file use this Whisper front end.
iOS
Use the built in Notes app and the built in features. TTS STT You may also want to try this Dragon Anywhere.
If you are okay with dictation, I would recommend using the built in Apple Voice Memos app. You can then use Whisper on Linux/MacOS and Dragon on Windows.
Android
TTS
The best solution is this app. It is very well featured and can use PDFs, TXTs, EPUBs and websites.
If you prefer an open source option you could try this TTS engine and this app to read text to you.
Another option, is to use your desktop to create an MP3 file and then use this app to listen to it. That app also works well for audiobooks.
STT
If you want real time results your only real option is using Google’s engine and the button on your keyboard. You may need to install this app for it to work. The only other option is to use Dragon Anywhere.
If you are okay with dictation, I would recommend using some sort of voice recording app such as Record You. You can then use Whisper on Linux/MacOS and Dragon on Windows.
Linux/MacOS CLI
TTS
If you are okay with using a Google or Amazon paid cloud API use this. If you don’t want to pay for things then use this. If you don’t like Google or Amazon and want to use an open source solution, then use this.
STT
You can use Audacity/Tenacity to record audio easily.
To transcribe audio run:
# Install Whisper
pip install -U openai-whisper
# To transcribe the audio
whisper --model tiny.en --output_format txt yourAudio.mp3
You may find the Whisper documentation handy as well.
If you prefer to use an open source dictation solution then you may like this.