Yeah; I'm definitely on the "Apple is overdoing it" train, in that their similar policy is unreasonable given there are no alternative options for developers on that platform.
But, Google/Play is different; developers who decide to distribute outside of Play don't receive any significant negative impact to their application outside of the marketing and operations that Play gives you, basically for free. There are other options, including no option ("go to my website and download the APK").
The pre-installation of Play on millions of Android devices is a weird sticky point. But, the most popular android devices on the planet (Samsung, Huawei) also ship with secondary (or, in some markets, primary) storefronts, and devs can distribute on those. Google set a norm with most customers, that all apps are on Play, but I also don't really see much tactile anticompetitive behavior from them in making it that way; its just the cultural norm, primarily due to convenience. I'd support government intervention to force device manufacturers to prompt users to install alternate storefronts on device setup, but its not the biggest of deals on Android.
Also; developers can monetize their "donations" via in-app purchases. I've seen tons of devs do this; either one-time or subscription, sometimes for little dumb non-functional stuff like extra theme colors, sometimes for nothing. I've paid for a few. Google will take their 15%. So, you're paying maybe an extra 10% on-top-of whatever you'd already have to be paying Stripe or whoever. Is the marketing, distribution, metrics, bandwidth, customer base, and even tangentially, developer tooling (Android Studio), worth that? The answer to that is different for every developer, but I think you'd have to be turning some huge revenue (some may say, some "Epic" revenue) for the absolute number underneath that percentage to start drawing scrutiny.