Wireless Hard drive

No. The speed of a wireless drive has never been the problem, it is the network access to the library that is not supported by Photos. This is still valid: Move your Photos library to save space on your Mac - Apple Support

To prevent data loss, Apple doesn't recommend storing photo libraries on external storage devices like SD cards and USB flash drives, or drives that are shared on a network.

It is for different reasons. You cannot use a network share, because the software does not support it. You would risk data loss, because syncing errors may damage the library. It is really a no-go to put the library onto network share.

The reason why Apple advises against using SD Cards and USB flash drives is the hardware. SSDs still store data in electrical charges, which slowly leak over time if left without power. If you keep the card continually in the slot it may work, but do not remove the devices for a longer time. Another problem are the limited write cycles.

Well that's what

Apple doesn't recommend storing photo libraries on external storage devices like SD cards and USB flash drives,

says, no?