The ORM Data Model Wizard (XPO) currently has no XAF knowledge/dependencies and it does not provide this functionality. Due to the great XAF flexibility, this requirement can be automated quite easily by writing a few code lines in the simplest and most popular cases.
You can override the ModuleBase.CustomizeTypesInfo(ITypesInfo) method and add the RuleRequiredField attributes dynamically for required properties. A similar technique can be used with the RuleValueComparison attribute based on the property's size. Examples:
How to avoid the SqlException and validate business object properties based on the NOT NULL and size state of underlying database columns
How to customize an XPO business model at runtime (Example)
The following additional concepts are required to implement this task:
eXpressApp Framework > Concepts > Business Model Design > Types Info Subsystem > Customize Business Object's Metadata
XPMemberInfo > IsNullable (you will have to access the XPO's XPMemberInfo object directly instead of the XAF's IMemberInfo, because the latter does not provide a similar property).