Connect iPhone headphones with 3.5mm plug to iPod nano

I thought one could connect headphones with a 3.5mm plug to an iPod Nano as it has a 3.5mm jack.

Article here would indicate that you can: https://support.apple.com/en-us/HT201869

However the plug is too large.

Headphones being used are from iPhone SE (1st gen). IPod Nano is 7th gen.

Anyone know the real specs for the iPod Nano jack so I can purchase an appropriate adapter?

Thank you,

Joe