Yes, this is possible by setting the following on your apps: definition as an example:
apps:
name-of-your-app:
command: some-command
daemon: simple
plugs:
... # plug any interfaces required here
See Snapcraft.yaml schema for the daemon documentation.
You need to put your application inside the snap package. There is zero benefit to using a snap package if your application is not packaged in the snap. When you update your application you need to rebuild the snap with the new code and publish it to the snap store in order for it to update your installed snaps.