theming – creating a custom report page with a table

Drupal 8.9.6, I’m trying to create a custom module admin report page.

I have a custom sub theme of seven called wd_admin.

I made a page controller that generates a table as markup, but want to use a twig file to render the html, and can’t figure out the theming.

It is using block.html.twig to render the content, and the first suggested template is block–wd-admin-content.html.twig. So I created it, and plumbed it in with hook_theme and hook_theme_suggestions_block_alter, but it affected the content on all admin pages, wrong move.

Seems like for this to work it would have to be specific to the page. What do I need to do to render this page, maybe a page.html template?