Searched "Android auto clicker" and got several lists back including this one:
Automate tasks with an Android auto-clicker app. These apps don't require root access and can help maximize your device's potential.
www.lifewire.com
If you want safe, a long running app from GitHub where anyone can inspect the source code is probably a good bet. Something like this:
An open-source auto clicker on images for Android. Contribute to Nain57/Smart-AutoClicker development by creating an account on GitHub.
github.com
No guarantees, of course. Might be that no one has inspected that source at all.
If you mean safe from Niantic's unprediable softban policy, it's probably fine. They care more about modified game software, not overlays. If Poke Genie and Calc get away with it, I can't see a clicker bothering them.
I also wouldn't look away from the screen, as the moment you switch from a 3 move to a 2 move you're in trouble. Unless you want to do all charged attacks manually anyway.