Yes, the Panasonic Lumix G9 II is compatible with the Samsung PRO Plus 256GB SD.
Samsung PRO Plus 256GB SD is V30 class. Clears: MP4 4K30 LongGOP (72 Mbps, requires V10); MOV 4K/C4K LongGOP (200 Mbps, requires V30). Does not meet the floor for: MOV 4K/C4K ALL-Intra (400 Mbps, requires V60); MOV 4K/C4K ALL-Intra (top tier) (600 Mbps, requires V90).
Limitation
Does not meet this camera's real per-mode write-speed floors above 200 Mbps -- the 400 Mbps ALL-Intra mode requires Video Speed Class V60, and the top-tier 600 Mbps mode requires V90 (per this camera's own fetched spec). This card is V30 class. Limited to LongGOP recording at 200 Mbps and below.
“Motion pictures with 400Mbps or less: External USB-SSD, SD memory card with Video Speed Class 60 or higher”
Last verified:
Compatibility inferred from spec rule (citations above are manufacturer-verified)