There are simply too many questions here.
I tried Electron Js to make application, but the problem is that, it takes extra memory in machine.
While the memory consumption of electron application is usually larger than highly optimized native applications, it is comparable to running chrome standalone. So switching from electron to a node based application (which user would need to run locally) does not save you a lot in terms of memory esp if the user uses chrome to view the web application.
If I have already installed chrome browser in the machine, why should Electron install another chrome in that machine.
Basically, bundling the runtime ensures that you can control the version of chrome in use in your application regardless of what the user has installed in his/her machine.
This also means that the browser engine you test against, is the browser engine that the user uses (on all platforms).
Some projects like electrino have attempted to address this by using the installed browser engine for electron like desktop applications, but as far as I know none of these efforts are production ready yet.
So, my question is, if I have any opportunity to do a node js application that runs locally in a machines browser.
Having said all of the above, there is nothing really preventing you from building and distributing a node based web applications.
For application targeted at technical (or technically inclined) users people usually distribute these applications either as npm packages or platform specific package managers (eg. scoop for windows, homebrew for mac, snaps for linux etc.).
You can also use a solution like zeit’s pkg to distribute your application as a standalone binary.
As far as I can tell, any app store for desktop operating systems will not allow distribution of web applications.
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solved Node Js application in client machine