Hello, @hostdz,
1- No, you can not, By default WordPress support only 1 front page there are no settings in the WordPress itself to set the different frontpages on different devices. There is a trick to making it.
First, you have to create a page and add the content to it in this way.
A- Desktop version content.
B- Mobile version content.
Once you created a page and add both device’s content on the same page then using the responsive feature of the Elementor you can hide the content from the devices. In order to know how to use the responsive feature please check this article: https://elementor.com/help/mobile-editing/
2- Actually, Yes, you can make a custom link instead of a page link on the phone button. See this image to learn how to set the custom link for the call: https://postimg.cc/k6jj3BFV
Regards 8Themes Team.