This is off the cuff, but if you created a page in WP with the slug “custom”, then created it’s own template page…
Then you could pull in the value of $ids = $_GET['id'], which might be “1200,1301”…
Now you’d have to do some sanitizing of the values in $ids but then:
echo do_shortcode( "[products id="{$ids}" orderby="title" order="desc"]" );