Gaming

Assembly line. It's budget factorio

I've been playing turn based gameboy games on my phone. Perhaps that would be a suitable candidate?

Thronefall got an android port. Not sure how to get it without google but I played it on steam, its like round based, you setup defenses and then fight off a wave. You can back out and come back to the next wave later, at least on desktop.

When you finish a level you unlock new perks and challenges so you can redo the levels to get better scores and stuff.

Farm RPG. Been playing for a couple of years.

Zhed. It's the most satisfying puzzle game I've ever played.

Cookie Clicker........... You click cookies.

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.

Not sure how "idle" this is, but little alchemy 2 is a great pass time for me at the moment.

I like this one, account is optional. No google at all.

https://f-droid.org/packages/com.team242.robozzle

or some classics

https://f-droid.org/packages/com.serwylo.retrowars

Civilization or a Civ clone could be good!