Raspberry Pi 5 with Raspberry AI Camera and NVME/PCIE drive?

You can try an SATA SSD adapter, I use one from Geekworm on my Pi4, it only uses a USB port,  I perhaps they have one for the Pi5 also.

There are several other options also.

Can I connect multiple PCIe hats to an RPi5?

https://forums.raspberrypi.com/viewtopic.php?t=368373

Posted by: @thespamcatcher

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You can try an SATA SSD adapter

Thanks @thespamcatcher, I already have a Pi-3 running on an external USB3-SSD drive from Seagate, no adapter required. Only things is that it "hangs loose" on the USB port with a 20cm cable beside the rPi case.

Another USB-SSD, from ADATA, didn't boot at all. The console showed lots of errors and delays when accessing the disk, though writing the Pi-OS with the official Raspberry tool on a pc went without problems and very fast (in a USB3 port). Possibly my power supply - a official rPi-3 one - was not powerfull enough.

@fransk 

I ran my pi 4 with a loose SSD or t thumb drive for a while and got tired of them being in the way. so I got the Geekworm/pi SSD adapter/hat (pi 4). I also have their fan hat above the 4, (a separate hat). The latest image and firmware allow you to select boot order, so I initially booted from a 16GB SD card, cloned it to the SSD, then grew the filesystem on the SSD so it used the whole thing. Then set the firmware to boot order of SD card, USB, then SSD so I could change things if it had a problem. Pulled everything but the SSD and booted from it. When I get around to it I am going to add a WIFI Manager so I can change my WIFI more easily. I have not looked for a USB only SSD for my pi 5 for the same reason you have, I would like to use the NVme for something else. Hopefully there is something similar. The Geekworm SSD hat is not compatible with the pi 5.

@fransk 

Raspberry has a new 47W power wall wort for the same price as the old 27W one.

@thespamcatcher I am preparing a nice, but expensive, case for the rPi 5: https://argon40.com/products/argon-one-v5-case-for-raspberry-pi-5 that has a (single) M.2 board inside. Apart from that, all the rPi connectors are brought to the outside with connectors of the case itself, including a normal size HDMI connector, thus eliminating force to the rPi connectors when inserting / extracting cables.

In stead of the included single-M.2 extension board they also have a dual-M.2 board that has a NVMe switch, and the latest rPi firmware should be able to boot from a NVMe drive behind the switch.
Pimorini also has a dual-M.2 extender board, which must be mounted below the rPi board.

Thus far my rPi5 boots from my the drive using an M.2-to-USB3 adapter. I installed the latest rPi-OS directly on the M.2 card using the adapter connected to my pc and the latest Rapsberry OS Imager tool. Plug-in the adapter in the rPi5 and it started up normally and blazingly fast (apart from the first-start actions and drive resize). At this point no need to update the boot loader on my (recent) rPi. No need to use a SD card.

Next step is putting the rPi and the M.2 drive in the Argos case, and first read the installation instructions. It seems that the M.2 extension board doesn't make contact to the rPi when the bottom is not screwed on.

Update: the rPi and M.2 SSD are mounted in the Argos case (with single M.2 adapter), put in a battery for the on-board RTC, and the system almost flies away: cold boot time to desktop is 10 secs. Installed and ran the Argos utilities to make the add-on board fully operational. In the raspi-config I switched to the experimental PCIe x3 speed which almost doubles the drive performance (the SSD is PCIe4 capable); not any problem so far. Changed to a 5A power supply as with the 3A supply there was a repeated system warning "low-voltage; not all peripherals could be working correctly, use the 5A power".
And of course the wonderful On-Off-(Shutdown Now) switch finally makes the rPi a real computer. 
Next step is to install the AI-camera, get a suitable cam-case, and run the AI demo's.