> In my phone "phone's app" I have the option to message on whatsapp next to each number, but when I click on it, whatsapp doesn't let me just message the number, it asks for permission to view all my contacts.

This works fine with Open contacts from F-Droid.

The coredump is sparse in elf format.

You're thinking to complicated. You can configure the coredump helper in a way that the kernel presents it with the coredump on stdin. So you drop privileges and self-sandbox at startup and only then start reading the coredump from stdin.

IIUC Ubuntu and systemd however choose to dump the process manually for some reason and for that you need to have same permission as the target process.

Google's local models as well (Gemini Nano/Gemma 3n)

No