I no longer use antivirus software on my desktop or mobile device, I have never had any problems.
I suggest that you don't install any app outside of the google play store. Even so, there are many apps that distribute malware and spyware that bypass the Google Play barrier. The only surest way to protect yourself from potential threats is to not install anything that isn't related to your own custody.
If you are a cautious user who:
- Updates the SO frequently, as well as the apps installed.
- Don't install apps out of curiosity, especially if they are suspicious, check the ratings and comments, check the sources (especially if they are a wallet).
- Don't trust those apps that scan your cell phone to clear the cache, you can do this yourself in the settings, just search. These types of apps are the biggest distributors of malware.
I would be alerted when my phone starts displaying pop-ups with ads inside or outside of apps, you probably have an app that contains adware and there is a high possibility that they are spyware too.
Use a hardware wallet, you will be 97% safe, on Android you can even send/receive transactions with your connected HW, now on iOS it's more difficult, unless it's a HW with Bluetooth! (I'm not a big fan of HW with Bluetooth).