If Google took a more reasonable cut, like 5%, maybe even 10%, then sure, I wouldn't be so bothered by them insisting that this app use in-app purchases for donations.
2. I don't think Google actually needs a 30%/15% cut to "support the Android ecosystem". I think they're charging way more than necessary, just because they can.
(Same arguments for Apple.)
Also, a donation is very different than selling something from a legal point of view. When selling, you need to pay VAT.
One could keep two apps, one paid and one free, but then on the paid one you're essentially paying 30% to Google and about 20% more to VAT. So you're effectively losing half the money and having to do lots more work to maintain two apps, and their subsequent ASO.
You then have the problem of writing and maintaining the code for the IAP, which isn't always trivial. But yes, absolutely do-able.
At this point it's the same thing as selling an invisible skin for your app. The fundamental issue is that of selling vs donating.
