I’m currently using the headless CMS Cockpit, which has the content field type collectionLink, which is a relational field that allows a content author to choose from all of the content entries of the defined content type and select one or multiple.
The headless CMS Directus, allows for one to many, many to one, etc. relational linking, that actually indicates the relationship on both content items linked.
This feature is super helpful for documentation sites, as there is a hierarchy of related content. Does Grav have anything similar or related?