I mean, it sounds fairly obvious that this isn't allowed. It is well known that Google (and Apple) do not allow you to have links in your app to payments outside of the ecosystem.
The problem for them isn't the surprise, it's the denial.
Apple allows apps to sell physical goods (otherwise Walmart would have problems), would the situation be different if the people who donated got T-shirts?
Google allows large players to have payment services that do not go through Google, as long as all of the money is directed towards a single person and is not in exchange of physical or digital goods.
Of course, that goes out of the window as soon as you're a small developer because then you simply get banned from the play store for doing this, your only recourse being talking to a bot that will never answer you.
The OP here is just asking for donations; users don't get anything in return.
The App Store Review Guidelines only say "If you want to unlock features or functionality within your app [...] you must use in-app purchase."
I haven't tried it (yet), but it looks like you might be ok with a Patreon link from an iOS app. The review process can be capricious, of course.
> Apps in this section cannot, either within the app or through communications sent to points of contact obtained from account registration within the app (like email or text), encourage users to use a purchasing method other than in-app purchase.
> (vii) Apps may enable individual users to give a monetary gift to another individual without using in-app purchase, provided that (a) the gift is a completely optional choice by the giver, and (b) 100% of the funds go to the receiver of the gift. However, a gift that is connected to or associated at any point in time with receiving digital content or services must use in-app purchase.
You may disagree with his reasoning, your use of that expression is unreasonable.
"Yes. I confess it."
"depriving Google of some precious money"
No, unreasonable it is not. These are very entitled quotes.
I suspect it's the last one that bothers you the most. However, keep in mind that Google has a monopoly on Android app delivery. (Yes, we will ignore the alternatives because they are not reasonably accessible to most users.)
Since Google has a monopoly here, any app that pleases some users strengthens the platform, leading to more users which leads to more apps, some of which generate revenue for Google. If there were a reasonable competitor app store for Android, this developer could drop Google and go give his app away for free on the other app store. THAT would deprive Google of more revenue because it would strengthen the competing delivery platform.
The only "entitled" party here is Google, because they believe they are entitled to a cut of all money possibly made anywhere from any app that runs on their "open source" platform - simply because they are the gatekeeper.
I am sorry this came up sounding entitled: I don't expect Google policies to change on this subject, and since this is not business threatening to me I just decided to write something I thought would be snarky and hopefully amusing to read.