There is another way to enable your JSP for the entire portal and, i.e. docking station.
You can create a hook and enable jsp in /html/portlet/dockbar/view.jsp using <jsp:include /> or <liferay-util:include /> or a simple <%@ include file="" /> (that was would be static).
<jsp:include page="/jsp/yourJSPPageToBeIncluded.jsp" />
OR
<liferay-util:include page="/jsp/yourJSPPageToBeIncluded.jsp" />
OR
<%@ include file="/jsp/yourJSPPageToBeIncluded.jsp" />
Note: the path may differ depending on where you will place the JSP.
Why do I choose the dockbar, because it is present on all pages of the liferay portal. This will not work if you open a pop-up pop-up window or a pop-up window with a "view and view" function or other custom pop-ups, since the dock is not in the pop-up window. For use in pop-ups, you need to redefine portal_pop_up.vm in your custom theme and write code, as suggested by @VikasV
$theme.include($themeServletContext, "/jsp/yourJSPPageToBeIncluded.jsp")
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