Actually iOS isn’t supported because the Qt Serial Port library the VESC Tool uses isn’t available for iOS. You could still have an iOS version and just not distribute it through the App Store (eg; release the source), it’s not real hard to open up an Xcode project and click the build button…
It’s only GPL’ed code that falls foul of the App Store, most other open source licenses are fine. You’d honestly struggle to find an app in the App Store that didn’t have open source code in it.
From a business perspective you want those iOS users, they’re the ones with all the cash 