I know Google doesn't like developpers accepting donations but technically speaking how would I do it? For PayPal you just open a link. Is there an easy way to do it with Bitcoin?
You can use a bitcoin URL that is handled by an installed bitcoin wallet, see this question or you can use an existing payment platform (like paypal) that handles bitcoins (paypal does not).
Here you have a guide and a "Merchant Services" list. They will handle the payment.