Just a quick posting that is long overdue. We’ve successfully used the Advanced Custom Field plugin to create Gutenberg blocks for a project to a client. This has made it so much easier for the client to customize their pages with the design elements they wanted. Each design element becomes a block.
The client was extremely happy with the results.
We created a git repo with a bare bones version to use when we start the next project. You can view it here.
We kept all the css and styling in the theme files for the blocks.