I just wanted to post about my niche finding!
The old and not very useful in most situations, 16Gb Intel Optane M10 makes a fantastic boot disk!
They are 5$/€ shipped on aliexpress/ebay and you have plenty of space for OpenWrt.
They sip power! 2W at full load and 8mW at idle. They come in 2280 and 2240 sizes.
They are normal nvme drives so you can use them in any machine. The are not limited to intel hardware.
If you machine used to have a wifi card (m2 e key), you can even buy an m2 e key to b key for an extra 3$/€ and use it to install your drive there like me. And of course, works in any normal m.2 nvme slot.
99% of devices that can boot from a nvme, can do it from the wifi slot.
Both the normal m.2 and the wifi card use the same bus (i think), just check that your board does not use the CNVi/CNVio protocol or have a wifi card withe/black list.
If you can not find any information in your motherboard manual or forums, it's probably because is no restriction. The few times that I have seen restrictions are in very specific models of laptops.
As OpenWrt does not need a lot of r/w, even the drive running as x1 pcie 2nd gen (normally the bandwidth designated for wifi cards) it does not matter.
If you need more space, you can add another drive to the probably empty m2 (if you have one) or any other disk and do heavy r/w without worries of killing the main drive.
I recommend the 2240 form factor if you are going to use them in the wifi slot, as most are vertical, and with the adapter they are more or less the height of a stock intel cooler.
I'm using one right now in my x86/64 machine. And I have for at least 6 months without problems. I think they are the cheapest storage option by far. (Without counting the couple of drives that you forgot somewhere around your house, of course 
)
Anyone also using them? Any opinions or experience with them?
