Voice input UI choice

This is a design question. I’m making an app where the user can input a request as text or speak the request. So far, I’ve designed it with a text input component and the user can click on the text input and type on the mobile keyboard. Or, the user can click a separate button and dictate their input (via speech to text). This works well but I’m wondering if it makes sense to have this separate button.

My iPhone has a voice input button that’s part of the OS keyboard and appears when I tap on a text input so do I really need the separate voice input button in my app? It’s a shortcut because the user doesn’t have to first tap on the text input but… would it be cleaner/simpler as a user to just use the built-in voice input that they’re used to?

For reference, this is the sort of UI that I currently have and I’m wondering if I should leave the microphone button or remove it?

For what it’s worth, this is what ChatGPT has to say about the matter:

If you think that providing speech-to-text functionality is a key part of the user experience, it might make sense to include a microphone button within the app. If, on the other hand, you think that voice input will only be used occasionally, it might be better to let the user use the built-in voice input button in the OS keyboard.