I want to keep my snap private on the store and want it to get refreshed from the store using terminal. Is this possible?
You can install any revision of your own snap from the store, but the client can only follow specific channels, which means you need to release the snap in a channel for the machine to be able to pick it up automatically as a refresh.
Once you release the snap in a channel it’s not private anymore. Then see comments from @noise below.
You can switch your snap from public to private (on your snap details page on https://dashboard.snapcraft.io). When a snap is private only you (the publisher) and collaborators can access the snap on systems where you are authenticated via