This model should be done more. Develop the product in the open, offer a fully functional open source version, and then offer a paid version on commercial app stores.

This can bring in some extra revenue for the project, plus covers the app store dev work.

I bet a bunch of users would buy it just to support the dev team. Plus I would argue an app store purchase (one click) can be done faster/easier than any donation flow I have seen for an open-source project.

Just something to think about.