Can I use Python for cross-platform development. If I can, how?

Answer 1

Can I make apps?

Answer 2

python is a cross platform scripting language. the script you write can be be run in different platform with the condition that you have python installed.
there's some case that it's not.
1- when using certain kernel functionalities like for example sniff 3g packets or injecting fragmented packets using scapy that some os doesn't support.
2-using a platform depending package like pywinpathk
3-being super dumb to call platform depending executable or binary like tasklist or lastlog...

Answer 3

yes you can.
Pyinstaller is a python module that take you python script or module and pack it into a standalone executable.
You need to know that this executable are not cross platform.
if you run Pyinstaller in *nix environment, you will get a Linux executable. And if you run in Windows, you will get a Windows executable.
the advantage is that you don't need to alter the code for every platform.