I can answer yes to all of these questions but still use a spreadsheet. I understand your point, but I feel even with these the line is still gray.
I just checked and my largest spreadsheet currently has 14,300 lines across 12 tabs. Each tab contains the same information just pulled from a separate form. So each tab is linked to a form to update automatically when someone submits a new response. We then process these responses periodically throughout the day. Finished responses are color coded so a ton of formatting. Also 7+ people interacting with it daily.
Then we have a data team that aggregates the information weekly through a script that sends them a .csv with the aggregate data.
The spreadsheet (and subsequent forms) are updated twice a year. It was updated in June and will be updated again in December. It’s at 14k now and will continue to grow. We’ve been doing this through a few iterations and do not run into performance issues.
Apple has very explicitly stated in very clear terms that the health app does not share data with other apps or devices unless you give permission. And as someone who has given that permission (twice, once to give a meal tracker write permission and once to link to my doctors office’s application for read and write) it’s for every application. It’s not a “hey you need to let everyone have access or no one”. You can get fairly granular.
There’s always the possibility of lying but usually when a company goes that hard on saying the same thing is so many different ways it’s legit. They don’t commit like that unless they know they won’t get in trouble. Those kinds of statements could open them to false advertising claims if it got out they were taking your health data.
Here’s a link to their privacy document which reviewed a good bit of info: https://www.apple.com/privacy/docs/Health_Privacy_White_Paper_May_2023.pdf