Showing a different page for mobile users

Hi.
I’m trying to figure out how to show two different pages for the same menu item: one for desktop users and one for mobile.
I found solutions that can switch the entire theme, however I want to keep using the same theme and simply show a different page from the same theme.

For example the gallery type I’m usi ng for desktop doesnt work well for mobile, but the theme includes a different gallery type which would be perfect for mobile. It would be perfect if I could only build a different page for mobile which uses the second gallery type (I dont mind linking the photos separately for each page).
Another example is a contact page including google map which is not needed for mobile and is not displaying well. I would like the mobile version to just exclude the map. A different page would do the work. (contact and contact_mobile).

Is there a plugin that has such functionality? Or perhaps a simple change in the theme? I can do some html and css but no php knowledge.
Thanks allot in advance!
Igor.