A tiny PC for HA and Frigate with M.2 support - which one?

There are three versions of Coral Accelerators with M.2 form factor:

M.2 Accelerator B+M key

M.2 Accelerator A+E key

M.2 Accelerator with Dual Edge TPU

Could you please write, based on your own experience, which tiny/micro PCs would accept one of the above-mentioned devices to work with Frigate?

I am looking for a device with a really small footprint and energy consumption, like PI4. But PI4 currently is unobtanium, so I am looking for an alternative.

You might have a look at this family of Intel x86 SBC’s, I have lost track of which Coral goes in which type of M.2 slot. So not sure if this meets your specs. As a B-Plan, not sure if Google still sells their USB Coral, however I have used it successfully under Ubuntu 20.04 LTS and Docker. However, I have been very pleased working with the MeLE and Ubuntu 22.01 LTS. The last machine I put a Coral in was a HP ProDesk 600 G1 Desktop Mini that I picked up on eBay for USD 100, the Coral PCI M.2 works fine in it. It is a PIA to figure out the various M.2 slot configurations. Might be hard to find the unit I used as it a bit old in computer time, and be careful of new/other models as the PCI/M.2 configuration can vary. Good hunting!

Rock Pi 4 has Pcie2 x4 lanes.

Rock 3a has Pcie3 x2 Lanes

Still sort of bugs me you need a riser for those and much prefer the Pico ITX format of the Rock5a which massively blows away a PI4 and has a 6tops NPU anyway but has 2x M.2 interfaces.
M.2 connector M key (bottom) for NVMe with PCIe 3.0 x4 lanes
M.2 connector E key (top) for connectivity with PCIe 2.0 x1

RockPi4 has an advantage that I think its now 100% mainline and has a ton of distro support.
Rock3&5 much newer products and offer BSP images as they garner more mainline support.

Its mounts on the heatsink and strange not to have one in the OKDO shop.

As another opinion point, I am hesitant to recommend any ARM based SBC other than the RPI family. IMHO, the ability to make and keep a Linux image solid for these boards is pretty limited. The ARM Linux hardware I have experimented with does not seem to have much staff focused on building and maintaining a LTS type Linux image. And that is what you really want for a home automation server. At best they are working on Linux graphics drivers for gaming, but for the most part the work seems to be almost all focused on Android images for these SOCs. The price of some of the ARM SBC computers is very good, as long as you are willing to limit yourself to 4GB of RAM, but getting network drivers, M.2 SSD drivers to be solid has been difficult for me. Most of the Intel or AMD SBC’s will install a stock Ubuntu or other x86 Linux image and drivers and hardware support just works.

Actually that is because you don’t use others and have no experience of available images that are also the usual Arm Debian & Ubuntu that RasPiOS is based on.
You need a feel for firstly the manufacturer but also how new the chipset is as the Pi was extremely rough around the edges when 1st released.
In the above I would suggest staying away for now from the Rock3 & Rock5 purely because they are relatively new SoCs and releases, but already have fairly solid images.
Pine64 also do a mature ROCKPro64 | PINE64
Khadas also are quite strong but the boards often carry a premium.

You always get the Pi Fan advising on not using others because without experience they choose one and had a bad experience, it complex but there are some very good and well supported boards out there.
Hence why the like of OkDo (RS) has started stocking them, but yeah others like the ‘strange fruit’ of Orange & Banana can be a bit lack lustre but even they have much improved.

The reality with Raspberry is much stock will not be avail to 2023 and you can suggest them all you like but people can not buy one anywhere.
There has literally been no stock for a year in the usual retail outlets, even scalper stock of hugely inflated prices is only available in miniscule qty’s whilst Raspberry continues to give preference to its commercial distribution chain.

Thanks. My budget is $100, including shipping, taxes, etc. So I will look towards Ebay.

Just wanted to know which small/tiny PC form factors would work for M.2 version of Coral.

You might have a look at this guys older videos, I found some of them helpful in my search for used x86 devices for home automation. I cannot speak to his newer videos as they seem ‘sponsored’

Good hunting!