Blockstudio is a plugin that lets you create custom Gutenberg blocks using PHP. Blockstudio has support for InnerBlocks and RichText without using JavaScript. You can use it to automatically enqueue styles and scripts. A full code editor is included and available from within the WordPress admin.
Since you are using PHP to create your blocks, you can use any custom field provider, such as ACF, Meta Box, JetEngine, Pods, etc that provides PHP functions for getting custom field values. It comes with its own 25 attribute field types, but noticed that these are stored with the block and not separately with the post as custom field plugins do.
Blockstudio does not create stand-alone blocks, you will need to have the Bockstudio plugin installed.