É um dado baseado na minha experiencia e carece de fontes mais confiáveis.
Eu publicava jogos na playstore antes de 2013.
Bem antes de eu ouvir falar de unity que durante muito tempo abocanhou parcela do 'mercado'.

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1. The Early Years (2008–2012): Java as the Default
When the Android Market (now Google Play Store) launched, Java was the absolute baseline for everything. Early iconic hits like Minecraft Pocket Edition and the original Android ports of Angry Birds were written entirely in Java or built using low-level native code (C++) bound via Java Native Interface (JNI).

2. The Great Shift (2013–2018): The Rise of
Cross-PlatformAs mobile hardware rapidly improved, 3D gaming demand skyrocketed, and the Apple App Store emerged as a major co-market, the industry experienced a massive migration toward Unity. Developers no longer wanted to maintain separate codebases (Java for Android, Objective-C for iOS).

3. Absolute Monopoly & Infrastructure Era (2019–2026): Unity Reigns Supreme
Unity has captured roughly 48% to 50% of the entire mobile gaming market share, powering upwards of 70% of the top-grossing mobile games on the Google Play Store. Java is rarely, if ever, used to build commercial, mid-to-high complexity mobile games today

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Performance
Um hello world java mobile: 1-5 MB
Um hello world unity mobile: 30-50 MB