Plugin template file ignores Themer

I can successfully use Themer for all the parts of the website, except one plugin.

I have a child theme, global header and global footer.
In WP customizer there are not much set as the header and footer is coming from a custom layout in Themer.

The plugin has a template override file and I can add it to my child root. Adjust it and is being pulled in.

The issue is that it is a gateway template. It doesn’t use WooCommerce page at all. It is also ignoring everything Themer. I can’t target it either as it’s not a content type. The url ends up something like:
https://foo.bar/wc-api/WC_Gateway_Blockonomics/?show_order=177&crypto=btc

This plugin template file is ‘content’ and gets wrapped in the child theme as I would have been displayed via the Customizer. So it goes to my child theme directory, but doesn’t load and completely ignore Themer.

As a test, I have been able to use
<?php FLBuilder::render_query( array( 'post_type' => 'fl-theme-layout', 'p' => 74 ) ); ?>

to pull in the actual layout and displaying it for the header. However for footer it is still loading the remnants of the Customizer footer after rendring my global footer injected like above.

I tried using this guide, but couldn’t get it to work
https://docs.wpbeaverbuilder.com/beaver-themer/developer/add-header-footer-and-parts-support-to-your-theme-themer

The plugin is Blockonomics and you can see the basic template files here
https://help.blockonomics.co/support/solutions/articles/33000243991-customizing-branding-checkout-page-appreance

Could someone please explain how I can ‘inject’ the Themer rules on this page render?
Thanks!