Ideally both iOS and MacOS, but my primary target is iOS.
For iOS you definitely need a paid developer account. See Developer Account Help > Supported capabilities (iOS) (in this context Apple Developer is equivalent to a Personal Team in Xcode, that is, deploying with an Apple ID that’s not associated with a paid account).
macOS is a more open platform, and so you could probably cobble something together once you’ve disable SIP [1]. However, I don’t think it’s worth heading down that path given that your primary concern is iOS.
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—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"
[1] System Integrity Protection