In-line with the strategy to roll out features on Cloud Service 1st, and 2nd add them to 6.5 Service Packs, the GraphQL support for Content Fragments will be released for 6.5 in the 2nd half of 2021. Most likely SP 6.5.10.

Starting AEM on Cloud Service Version 2021.01, field level validation options have been added. At the time of writing, there is, for a text field: E-MailURLCustom (allows to provide a regex to validate) For other data types, such as Content Reference allow to configure file type and image size const...

The product team is working on supporting Tabs within the CF Editor. A form can be split up - using tabs as UI element. This helps to make long forms easier to navigate, and might help in this situation. Currently scheduled to ship earliest with 2021.04