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.

InsideOut Solutions - Ozette Plugins

A simple mobile redirect plugin for those who use a separate website URL for their mobile content. Simply put in the full path URL and you are ready to send users to your mobile-only content.

Simple Mobile URL Redirect

This plugin allows you to put in a full path URL to redirect mobile traffic to.

Set WooCommerce Payment Gateway by URL vs Simple Mobile URL Redirect