When you’re doing any kind of post list/grid, you’ve got an option for a custom query string. So, you can pretty much do anything there that you could put a WP query string. — On the post grid/list page templates, you can add a custom field called “query”. On the post grid/list shortcodes, you can pass in a parameter called “query”. And on the post grid/list elements of the layout builder there should be an option that says “Custom Query.”
And thanks! I’ll checkout the login form thing.