It's no problem
About the drivers:
I can't confirm for a fact they will work out of box myself as I stumbled across the SATA cards merely hours before I posted.
According to the Amazon reviews from customers using Linux with the cards, it has no issues and is Plug and Play.
this was one of the customer reviews:
"Simple device, has a fast controller. I use it in Linux for software raid / ZFS. No driver needed, the additional controller just showed up where it should, on reboot. Recent vintage Linux, Kernel v3.1. I assume the driver was built into the Linux kernel already so nothing to install."
JunOS according to Wikipedia is based on FreeBSD, which is similar to Linux, but not the same. I'm hoping the cards have drivers present in FreeBSD, and I feel it's somewhat likely, but again, not guaranteed.
I found them because I'v got an older(Atom) mini Dell laptop which can't/doesn't do much. Opening one up revealed the one I have in particular has 3 mPCI connectors
After I found this out, I came here because I plan to make it run XPE, but I noticed this post which is somewhat similar to what I plan to do. (a Laptop is an SBC after all )