Donations and a webstore in an app. Does it attract a 30% cut still? 2021
You totally can get approved as a non-profit and have direct payments via in-app browser and avoid all fees on the transactions.

Approved nonprofits may fundraise directly within their own apps or third-party apps, provided those fundraising campaigns adhere to all App Review Guidelines and offer Apple Pay support.

Also, the small business program offers significant relief for discount to IAP fees if you want to go IAP or the review / approval doesn’t go your way.

https://developer.apple.com/app-store/small-business-program/

To reach the equivalent of 30% fee you have to be a whale (tens of millions of dollars in IAP) on the store now, not that you start out at that level.
I would not mix goods and services with charity unless you’re sure of how you’ll represent it to the review board and have assistance from a financial professional and a lawyer on retainer so you have contract advice and are not just doing this on a whim as a sole developer. Having official recognition of your charity will go a long way, but you also need guidance on Apple’s contracts to know what they mean specifically to you in many cases.