That's not how flatpack works; the executable is hidden in a container and you need to set up the whole environment to be able to call it. Delivering a well-isolated, not-to-be-run-from-outside environment is the whole point.

Some users download the DEB package and install it manually and manage upgrades completely manually. This is useful in situations such as installing Docker on air-gapped systems with no access to the internet.

Why did I put the kdb in the snap file system? Because the app is sandboxed, so I had no choice.

By design, snap apps have no access to /etc. They live in their own little world, but instead of a normal chroot, they are splatted all over the standard Linux filesystem layout. With other bits mounted hither and thither. Its a mess, and subject to change with each release.

The application is executed in an encapsulated, ring-fenced way, so its files can’t interfere with those on your computer. You can even install multiple versions of the same application, and they won’t cross-pollinate or fight amongst themselves.