Thunderbird is great and was my main email app for a decade – until I de-googled my life. I think settings were a horrible mess, but after that UX sending/receiving email were great.
Those were the days. Former Nokia (N9 Meego) employees formed Jolla and it is still alive. They nowadays sell tens of thousands of Linux phones, so not taking over the phone market.
If quality training data is the most important piece regarding to AI, expect everything to be collected and analyzed. Don't even trust OS containers but run AI on separate hardware