Desktop without a doubt. I installed some games to my phone and I tried to play them but it lags and stutters, not good, desktop no problem. The only thing worth using the mobile for is social use and reading. Also forget using mobile for watching movies since it's more enjoyable on a large screen.
This is a post from 2020 lol
For anyone new checking in though my recommendation is a few games on Steam, they are:
Learn Japanese To Survive! Hiragana Battle
Learn Japanese To Survive! Katakana War
Learn Japanese To Survive! Kanji Combat
They are made by the same company and if you enjoy JRPG...