I was able to generate Survey URL and the survey URL can be accessed on a non SAP handheld device but the screen is not mobile compatible.
This is how it looks :
Are there any theme changes we can push from CRM to make it mobile compatible .
The Edge mobile compatible add on , makes it look like this but this for SAMSUNG device but this is not how it actually looks on device above :
Standard theme: no, they were all designed in a time that Internet Explorer was the recommended browser for SAP Web Applications (long long time ago, mobile was still on early days with WAP protocol), never were modernized to the new web world.
Theoretically you can create your own responsive theme (CSS), upload it to CRM_SURVEY_SUITE repository, and use it on your survey.