If it's not sensitive data for a quick and dirty hack you could use the HTML web storage feature to store a value from one portlet to retrieve in another. Probabbly with a DIV. You could use jQuery to quickly append the value into the receiving DIV. You can then say detect if the local storage is already filled and of the same value to avoid repeating the copy again.

https://stackoverflow.com/questions/40791207/setting-and-getting-localstorage-with-jquery

Or do the same using standard Javascript
https://blog.logrocket.com/localstorage-javascript-complete-guide/

Esentially you're copying one part of the DOM to the other so you could try this on a test html page on your desktop and open in the browser without doing it in Liferay. Once you got it going copy the storing bit in the first web content template and the retriving bit in the second web content.