Is it secure to use Apple Pay and Google Pay?

Absolutely! Every time you pay using Apple Pay or Google Pay, your actual card number is sent to the merchant encrypted, which ensures that your card details are safe.
What happens if I loose my phone?

For Apple devices:

If you lose your Apple device with Apple Pay activated, you can stop all transactions from the Find My iPhone service. All you need to do is to place your iPhone in lost mode. Even if you fail to do that, the thief would need your passcode, Touch ID, or Face ID in order to make purchases.

Furthermore, Apple also has security measures to prevent sellers and third parties from collecting your financial information. When you make a purchase using Apple Pay, the merchant never sees your data. Additionally, Apple doesn’t store your card numbers on the device or on its servers.

For Android devices:

If you lose your Android device, the thief would need your passcode, Touch ID, or Face ID in order to make purchases with Google Pay.

Furthermore, Android also has security measures to prevent sellers and third parties from collecting your financial information. When you make a purchase using Google Pay, the merchant never sees your data. Additionally, Android doesn’t store your card numbers on the device or on its servers.