Idle Champions of the Forgotten Realms has an Android version. It’s F2P, though with many ways to buy stuff, but you can totally enjoy that game without spending a penny. Did so for years, though I eventually spent a few bucks as a thank you, given I have about 8000 hours logged on the steam version.

Also Watcher of Realms is a standout of the Gatcha like hero battlers which I much prefer to the likes of RAID.

Unsure of how much you need a Google acount though as I use mine for Android stuff anyways.