Yes, that was the issue. The version of core jar in ui.apps was an older version which is why I couldnt see my servlets in action. Thanks for your help 🙂

Firstly is it author or publish ? is servlet path getting resolved ? or is it getting resolved and throwing an error while executing ? are your getting 4XX or 5XX error ? is the servet using any system user which you dont have ? are there 2 servlet in instance which has the same path. ? If possible any stack trace if its 5XX issue

@aradhyakasat, an example can be found here https://aemcorner.com/include-external-resource-in-aem/