Brian Henry

Add <code>?payment_gateway=preferred_gateway_id</code> to links in emails you send to your customers, and when they reach the 
checkout, that will be the selected payment gateway.
A WordPress filter exists so the text in the URL can be set to whatever you prefer.
<a href="https://github.com/brianhenryie/bh-wc-set-gateway-by-url/" rel="nofollow ugc">Technical detail is on GitHub</a>.

Set WooCommerce Payment Gateway by URL

Set the WooCommerce payment gateway in URLs sent to customers.

Marco Milesi

WP Post Redirect allows you to seamlessly redirect individual posts to external URLs or internal content. Once activated, a new metabox appears on the post edit screen, letting you specify a custom redirect URL or search for an internal post/page. Great for affiliate links, content curation, or moving content.
Features: 
* Add a redirect URL to any post via a simple metabox. 
* Search and select internal posts or pages for redirection. 
* Set custom HTTP Status codes (301, 307, 308) globally or per post. 
* Option to open redirects in a new tab and allow <code>rel="nofollow"</code>. 
* Highlight posts with active redirections in the admin area. 
* Dashboard options page to manage all redirections with CSV Export. 
* Backend column to mark posts with redirect enabled. 
* Lightweight and easy to use. 
* Fully compatible with the latest WordPress versions.

WP Post Redirect

Easily redirect your WordPress posts to any external URL with a simple metabox. Lightweight, efficient, and perfect for SEO!

Set WooCommerce Payment Gateway by URL vs WP Post Redirect