Can I use my iPad to unlock my iPhone

No, but you won't need a Mac or PC either if you follow the instructions in the Apple Support document below:

How to remove your iPhone, iPad, or iPod touch passcode without a computer - Apple Support

No. The iPad may not be used to unlock your iPhone if you forget your passcode.

You can suggest this feature directly to Apple by leaving a product feedback here 👉 Product Feedback - Apple 

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