Have a look at the 'youate' android app in the play store. It provides a visual timeline of the foods you have eaten, relating that to your health and allows you to store notes on recipes.
The only 'food diary' that I know of that, that also has a web app is MyFitnessPal but it doesn't meet your criteria as it's complicated and focused on calorie counting.
It is not open source, but it is free -> Free version.
It is cloud based (OneDrive)
Privacy? It is not a zero-knowledge solution, so you have to trust. See privacy section below.
Platforms: PC (Win7+, Pre-installed on Windows 10), Mac, iOS, Android, and the web
Can be used standalone, but of course it integrates well with other 365 apps: ...
I can strongly recommend Conversations for this, which I'm using for years happily. The app is available from the privacy-friendly F-Droid as well as on Google Play if you insist. By default, it suggests you creating an account at their server (conversations.im), but you can easily use your own (I do).
Conversations is also the most complete Android client ...
The android app that is suitable in this scenario is - 'Advanced Call History'.
This app is one of the apps in the corresponding app listing by Izzy (moderator for software recommendation stackexchange site). Thanks Izzy for coming out with this wonderful app listing.
'Advanced Call History' app can read call and sms log and generate reports grouped by ...
QOwnNotes is a flexible solution that can sync with various clouds of your choice like ownCloud, Nextcloud, Dropbox, Syncthing, Seafile or BitTorrent Sync... Looks like any file syncing software is supported, but it'll work better if you have a server of your own and use platforms with a special note taking API like ownCloud or Nextcloud
It can also import ...
I have spent some hours under this issue and via lots of testing I found that when you put a white border around the aztec code image, then it works quite well and fast :-) I use it in my app: //for the barcode bitmap (string) scanning: implementation 'com.google.zxing:core:3.3.3' //FOR THE CAMERA SCANNING: implementation 'com.journeyapps:zxing-android-...
I'd suggest ColorNote
simple notes application: Very Straight forward
shared between my laptop: available in the Windows app store, Easily syncs between devices
has its own cloud: can backup to it's own servers
venerated as secure? Option available to encrypt data
There are some Google solutions I think might help.
Edit: they all need a Google Account (Login) so it dosn't meet all your requirements.
Google Maps has also a "share location" function, but not an "emergency button"
Probably preinstalled Google function called family link
Google Trusted Contacts Android App
Evernote is another cross-platform solution which I've used for almost 10 years.
It has versions for Android, iOS and Windows;
In Windows, it can be installed both traditionally via a wizard and as an UWP app via Windows store (just go to https://evernote.com/download on your device).
You can find more information regarding privacy and security here. It ...
Google Keep is available on web, Android, iOS and all platforms that can run Chrome. There are 2 official extensions you can find on the store: Google Keep Chrome Extension and Google Keep - Notes and Lists. I have no idea what the differences between them are but both can run offline and can be pinned to the taskbar to run as PWA desktop app
I have been using Simplenote and Standard Notes for years.
Both are FOSS and have their own mobile apps. For desktop I use their web editor, but they also have Windows app if you want to use it in desktop while offline.
I invite you to have a look at my application SilentNotes;
It is a FOSS application which I have developed with a strong focus on privacy.
The notes can be synchronized end-to-end encrypted between multiple Android and Windows devices and can be self-hosted. Currently supported are the FTP protocol, the WebDav protocol, Dropbox, Google-Drive and One-Drive.