From what I could find it does not have a fully supported barrel. I recommend asking Glock for conformation https://us.glock.com/en/Customer-Service

Hi and welcome to the forum. For the purpose of reliable feeding, no Semi-Auto has a "Fully Supported" chamber, just more supported. Key points about the Glock Marksman Barrel:
Improved accuracy: The Marksman Barrel design includes a tighter chamber and enhanced polygonal rifling for better accuracy compared to standard Glock barrels.
Gen 5 feature: Most Glock Gen 5 pistols come standard with a Glock Marksman Barrel.
Target-style crown: The barrel crown is designed with a target-style profile for consistent bullet exit. This load will be fine in this model. Cheers, stay safe and enjoy!