If you want to publish a client Infopath form, you 'll be working on a Sharepoint Forms Library. Nintex Forms (to build your mobile option) is not present on that type of library.

I imagine a workaround, creating another custom list to publish your mobile form, then a workflow could adapt/migrate that content to your Forms Library.

That format when I finally got it formatted did not seem to work – maybe it’s still not the correct format?

You can as well create an Infopath form for the "Form" content type in your library and Nintex Form for a second, not "Form" content type. But it is not possible, as Fernando mentioned, to create a Nintex Form for a "Form" content type

Regards,

Tomasz