I launched the book the 8th of February 2020. Here's what happened:
Here's a short video explaining the tools I used for the book itself.
For the landing page: Hugo (I've a good process for Hugo stuff, I can deploy one in 10min) with a theme I've adapted for my needs.
Selling platform: flurly. Fast, great UI, super good customer service, and more money in the creators' pocket.
I feel it's pretty good but... I've no prior experience so I'm not sure. Compared to my expectations I'm in heaven, I didn't think so many people would be interested by this book.
I stopped sending newsletter. Its purpose was only to brainstorm with the people who were the most interested by the book.
That said, people buying the book are on a special newsletter where I'll send the updates of it. I'll still take feedback from there, asking what would be the most relevant for them to see in the future updates.