I’m adding some tags for tips as I find them.
I found this tip helpful when debugging what the WordPress Block Editor (Gutenberg) was actually doing behind the scenes.
Find the post id (in the edit url there will be a field for post (e.g. post.php?post=121&action=edit). Using the WP-CLI tool you can quickly view the source of the post (assuming you have a very basic post with just the block you are developing) by running:
wp post get 121 --field=post_content
This will display the content showing the HTML as it is stored in the database — including the attributes for the block!