“Simple widget display conditions” is a plugin that sets display conditions for WordPress widgets. You can specify one by one on the widget page. Check the check box and specify the article or category ID.
License
Image banner-772×250.png / banner-1544×500.png / icon-128×128.png / icon-256×256.png license: CC0 from https://pixabay.com/ja/illustrations/%E9%B3%A5-%E6%94%AF%E5%BA%97-%E5%BA%A7%E3%82%8B-%E3%81%99%E3%81%9A%E3%82%81-3726473/