Latest Linux distros come with Sinhala support by default(remember to select Sinhala while installing).See other sister sites such as Tamil Wikipedia and Hindi Wikipedia to understand its capabilities. You cannot use non Unicode fonts to search in Wikipedia. It is Wikipedia's policy to use Unicode fonts in international sister sites. And not Kaputa or Kandy or eKottu? Unicode is the international standard for non-Latin scripts.Helakuru is a mostly used Keyboard app among Sri Lankans in 2020.If you don't have Google Playstore installed, then you can download the Helakuru APK version.
If you want to type in Sinhala using your Android smartphone, you can download the Helakuru Keyboard from the Google Playstore.You can type in phonetics, Wijeysekara layout or Singlish (ea kiyanne mehema type karana eka) and the program will type it in Sinhala on any open window (MS Word etc.).It's a small background program that intercepts what you type and converts it to the Sinhala unicode format.If you are using a version of Windows other than XP SP2, you can use the FutureSinhala keyboard driver to type in Sinhala unicode.
Note: you will need to have your XP CD handy. You can copy and paste what you write in Wikipedia.