Hi @gregy68980908 ,
Yes you can do this functionality with the spa react and pass the parameter. This parameter will not effect the rendering of the SPA react.
For trying it out.
1. Get the AEM Spa Journal Project https://github.com/adobe/aem-sample-we-retail-journal
2. Change the Navigation.js in react to add your '#userHere' in the getLink().
Please Note, later you have to programmatically expose the props for each component to be added in the url of react component.
3. Build and redeploy clientlibs to the aem.
If you click on any link on the navigation the browser will display react spa with the parameter.