SATA SSD vs PCIe NVMe Older Computer

NVM Express can nvme be used in m 2 slot 2 slot, but not both concurrently Check your mobo user manual for details 12:54 Go to channel candy bars slot machine 2 PCIe adapter ONLY supports PCI-e NVMe based M Key , NOT supports any SATA based SSD Fit for PCIe x1x4 x8 x16 slot

candy stash slot 2 slot is m-keyed only, so an NVMe will physically fit My question is, if an NVMe drive fits in a modern board's slot, will it work?