Hunt on ebay for a crappy old Windows CE based phone? I've had several (before Android was a thing) and you can program in many languages on them (providing you can still find the apps - I've still got a local repository somewhere). Also the original version of Visual Studio.NET and VS 2005 both supported Windows CE as a target so you could program apps in c# and copy them over.

Windows CE on phones was marketed as 'Windows Mobile' and the latest version was 6.5:

https://www.google.co.uk/search?q=window+mobile+6.5&hl=en&tb...