One of the cool things about writing free software is that there are companies that will provide you with their services gratis. Like #gitlab providing a free ultimate plan so that my CI doesn't have restrictive limits, or @Codemagic giving free access to mac buildmachines for iOS. Without the latter I wouldn't have been able to do an iOS port of Migraine Log.
And then there's Apple… charging me 99 USD/year to publish my free app.