I'm working on a pi zero version of my own at the moment.
The National Rail Enquires api's (Darwin) are free to use at personal (and surprisingly large) scale. They may be SOAP but still easy enough to talk to with some simple python. https://www.nationalrail.co.uk/46391.aspx
jsingleton|6 years ago
I wrote a proxy to make it easier to use (https://github.com/jpsingleton/Huxley). Been meaning to port it to .NET Core when I find the time. There is also an old Python client here: https://github.com/HackPartners/darwinrest
You can find many more resources in the community (https://wiki.openraildata.com/ https://github.com/openraildata https://groups.google.com/forum/#!forum/openraildata-talk). We're pretty friendly, say hi.