Hello,

Here’s how you can create a new widget by following this guide:
How to create a custom WordPress widget.

For using a widget in specific categories, you can use the WOODMART WooCommerce Layered Nav Widget. It has an option called “Show on Category” where you can choose the category, and the filter will appear on that specific category page.
https://snipboard.io/cKGYJa.jpg

Best Regards