Keep an eye on Release information.
"Pixel 4, Pixel 4 XL and Pixel 4a are end-of-life and shouldn't be used anymore due to lack of most security patches for firmware and drivers. We're considering porting them to Android 14 to continue providing extended support longer than initially planned to keep them as a way to preview the current version of the OS despite them not being secure. It will be a significant effort to port them properly without lost functionality and we're looking for a new developer to fund rather than reassigning any developers from their existing work on the OS."
According to the GrapheneOS Release page, the Pixel 4a (5G) will be receiving Android 14.
https://grapheneos.org/releases#2023101300