Yes, the Nikon Z8 is compatible with the Samsung PRO Plus 256GB SD.
Nikon Z8 Slot 2 accepts UHS-I SD cards. Samsung Pro Plus is UHS-I V30 (~90 MB/s) -- meets the Z8 minimum for basic video recording (UHS Speed Class 3 required) and still photography. Cannot record video at high frame size or rate, which requires a minimum 250 MB/s SD card per Nikon specification.
Conditions for compatibility
Compatible for still photography and basic H.265/H.264 video recording (UHS Speed Class 3 met). Cannot record video at high frame size or rate (requires 250 MB/s — Samsung Pro Plus at 90 MB/s UHS-I V30 does not qualify). N-RAW and ProRes RAW HQ are CFexpress Type B only. Not recommended for demanding video workflows.
Limitation
UHS-I V30 card. High frame size and high frame rate video not possible. N-RAW and ProRes RAW HQ not available to SD slot. For serious video work, use a card meeting the 250 MB/s / UHS Speed Class 3 threshold Nikon specifies for that tier (CFexpress, or a UHS-II SD card rated for that speed).
“CFexpress or XQD cards with a maximum data transfer rate of at least 45 MB/s (300×), or UHS Speed Class 3 or better SD cards, are recommended for video recording and playback. CFexpress or XQD cards with a maximum data transfer rate of at least 250 MB/s, or UHS Speed Class 3 or better SD cards with a maximum data transfer rate of at least 250 MB/s, are recommended for recording and playback of videos with a high frame size or rate.”
Last verified:
Compatibility inferred from spec rule (citations above are manufacturer-verified)