Hi Benjamin,
You could use Hook element to achieve this.
https://docs.generatepress.com/article/hooks-element-overview/
https://docs.generatepress.com/article/hooks-visual-guide/
1. Go to Appeared > Elements, create a new Hook element. Choose generate_inside_container
as hook,
2. Paste the short code from WP show posts to the content area, remember to check the Execute Shortcodes box.
3. In Display rules, choose Front page as location.
Let me know 🙂