Your point about needing a dataset made me think about how a post on hackernews like this may be a good way to get data. How many people would contribute by reading a prompt if they visited a link like this and had the option to donate some data? That would get many distinct voices and microphones and some different conditions.
The article mentions that they used a dataset composed of 100 hours of audiobooks. A comment thread here [1] estimates 10-50k visitors from a successful hackernews post. Call it 30k visitors. If 20% of visitors donated by reading a one minute prompt, that's another 6,000 minutes, or, oddly, also 100 hours.
Seems like a potentially easy way to double your dataset and make it more diverse.