Can I share any QlikSense app via link with other users which doesn't have QlikSense (for read only mode)?
No. They would need to access via the Hub and would need to use a token. You could create them as a user and assign them a login token instead of a named user if they are not going to be accessing the app often.
Otherwise you would need to use the Cloud. But you would have to export the app from the QMC and then upload it to the Cloud and then publish it there. Kind of a pain. Also, no way to reload the data in the free Cloud. You would have to repeat this process every time you reloaded the app on the server.
Keep in mind that they don't need Qlik to access the app. They just need access to the URL for your hub using their browser. But once they access an app they are technically a Qlik user.
With Qlik Sense Enterprise you can set it to "No Authentication" which essentially makes your instance or application public. Then it's up to you who gets the links to view your content.
Why would a business do that? I can see if you opened your Qlik Sense to your outside customers or vendors. But you would want to really control that access through the Proxy and Security Rules I would imagine.
First of all, assuming your data is not very sensitive and can be consumed by the public:
Not saying it's appropriate in many cases, but it is an idea.