That is assuming:
#1 You want your project based on Python, nothing against Python
#2 You do not have an existing code base in some other language that would need to be ported at $$$.
#3 You want to base your project on an open source foundation.
The idea that commercial programs should be on Linux because I like the OS or more, I do not like another OS is not going to convince the folks putting up the money, to put up the money.
I think programs running on some flavor of Linux would be great. Will I invest money in it (I also have bills to pay), no.
#1: No, wxWidgets is C++ with bindings to many other languages, one of them being Python. That's only one example of a cross-platform GUI toolkit though. There are many others, like Qt for example.
#2: Almost all languages have the ability to interop with other languages.
#3: That is a risk, but so is basing your application on a company's proprietary API. The risk is that someone else maintains it and may stop at some point, not that it's open-source.
The value proposition for Linux is not *only* that I like it more, it's just that -- the value.
The Linux desktop has come a long way. Many of you have probably tried it in past years and been disappointed. But right now, it's very good. If you were disappointed in the past, you should try it again to see how it's improved.
But anyway, the value:
1. Can run on older hardware and still be faster / more responsive
2. Free software that you can load along with it, such as LibreOffice (to replace M$ Office)
3. No Windows licenses to pay for or deal with
4. More secure and/or not much malware out there for Linux, don't have to pay for commercial antivirus or worry about this as much
5. blah blah blah, ranting now
6. in general, a lot less BS to deal with