I think I figured out the second use case myself. I thought Gutenberg handled the CPT rendering differently but apparently I just needed to create a single-CPTNAME.php file in my child theme and edit that. I assume that is still the best practice?
The first use case, accessing the parent CPT ACF fields from a block still have me stumped! 🙁
Welcome to the Advanced Custom Fields community forum.
Browse through ideas, snippets of code, questions and answers between fellow ACF users