Can a friend send me money from his Paypal account to my Apple Cash?
Can money be sent from another persons non Apple Pay / Apple Cash accounts to my Apple Cash? Eg from Paypal or Gcash?
No, the transfer systems are closed systems. In other words, it works Cash app to Cash app, Venmo to Venmo and PayPal to PayPal. Crossing over requires disclosing bank account information or debit card information.