M.2 NGFF vs NVMe - compatibility

Are there M.2 controllers, that do not support NVMe?

I am trying to understand, if an external m.2 USB controller will work with the M.2 NVMe drives I have.

The drive spec says "Supports M.2 (NGFF) drive of any capacity".

Does that mean it is not compatible with modern M.2 NVMe drives?

There's no such thing as a "M.2 controller". The M.2 slot provides direct PCI-Express and SATA AHCI interfaces – NVMe drives are full-on PCI-Express devices, with the NVMe controller being on the drive itself.

There are M.2 slots which only provide SATA but not PCI-Express, or vice versa, and while (AFAIK) it's rare on actual PC motherboards, this seems to be very common for M.2-to-USB adapters – many of which only support SATA because adding PCIe support would've been much more expensive. (And the ones which support PCIe often omit SATA...)

So if the USB device's specs do not explicitly say it supports NVMe, there's a high chance it doesn't.

While technically NGFF is a synonym to M.2 AFAIK, some/most vendors refers to M.2 SATA with the former.

It's worth noting that there is/are chip(s) (from Realtek) on the market that can bridge both SATA and NVMe drive.