xfce4-terminal + bash.
The only tweak for the terminal is a custom light theme, the only tweak for the shell is a custom PS1 to show current git branch and time.
Blank spaces are color coded so for easier detection, I can edit the file if I need to, and there are diffupdate commands for piecemeal merging of sections of the files.
Short answer: no, I would never subscribe to something like this.
Long answer: I would never trust my health or lifestyle data to a non-government organisation, and I would never pay for unreliable information based on guestimations.
Thanks for your feedback. Agreed, data protection is a big topic for apps. Thinking this may be relevant for those who pay for health/fitness subscriptions, to get a different perspective on the outcome of their activities. Agreed though, life expectancy data is based on large studies/populations, so can't be 100% accurate at each individual's level - more just an estimate as you say.