They do both Full Business op up AND biz seat with econ service op ups. I have received the "biz seat with econ service (one tray meal, no amenity kit etc)" every time (when I was a Delta Silver Medallion aka Sky Team Elite) like twice. Your ticket will be an economy ticket with a biz seat number.

However, my ex-bf at the time was a Morning Calm Member (also SkyTeam Elite) and he received several full business upgrades. Issued on biz class stock.

When I was bumped up to biz seat with econ service, they did move full biz passengers up to the front cabin and it was literally only us in that section of the cabin.

That flight must have been MASSIVELY oversold for that many people to get any kind of upgrade. Every time I fly KE I just straight up ask how oversold the flight is and if the upgrade is possible (because the first time I asked and every time they actually genuinely understand and check).......and they only upgrade if the flight is absolutely 100% full. One empty seat? Not a chance of any op up whatsoever.