Wordpress API - Allowing 3rd Party Websites to List My Posts (Events) in Custom Ad Widget

CUSTOM WIDGET AIM Partner Website to be able to display our posts(events) on their website in the form of a custom widget which link to us.

I have a website that lists events (posts). For example

1. NYC vs LA - Barclays Center, Brooklyn - 2023-01-01
2. Random Concert - Barclays Center, Brooklyn - 2023-01-02
3. Sporting Event - Barclays Center, Brooklyn - 2023-01-05

What I need is for 3rd Party websites (Partners), (that I give access) to be able to access the events based on the parameters they want.

Example: We list all the events from New York on our New York Page.

Partners want to display on their website, all our events (in the form of a widget) in New York that are sporting events.

1. NYC vs LA - Barclays Center, Brooklyn - 2023-01-01
2. Sporting Event - Barclays Center, Brooklyn - 2023-01-05

An overview plan or guidance would be appreciated. I would like to know what the best way would be to implement this. Most Partner websites will be WordPress but some custom if that makes a difference.

1. Partners would need an API key to get events.
2. Ability to create their own custom ad.

Thanks