How to Share JS Variable values between Razor .cshtml and Html file (a Html solution in the same solution)

I have an MVC Razor solution in which I have a separate HTML project(folder name Sub_HtmlProject from the attachment).

Question: How to use a JavaScript variable**(razorJSVar)** defined in this Razor **_Layout.cshtml Views > Shared > _Layout.cshtml

to

Sub_HtmlProject > index.html

Please note I would like to have a solution without using LocalStorage, Session, DB storage or any browser storage options.

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from How to Share JS Variable values between Razor .cshtml and Html file (a Html solution in the same solution)