A few months ago I toyed with the idea of using just the internals of a 2.5 inch SATA SSD mounted to a Pi 3B.
It even has mounting holes that matched the spacing of the JBTek case I was using (well, 2 out of 3 anyway).
I decided against it because the SATA connector felt a bit flimsy without support from the case. Making a custom bracket (perhaps by cutting the existing case down) could solve that problem, but seemed more trouble that it was worth. It was reminiscent of the old X850 v1.2 mSATA expansion board
that mounted over the USB and Ethernet ports (except the X850 was more expensive and didn't reboot reliably).
Of course you'd still need a USB-SATA adapter, and at least you have a choice in that (my Eluteng/TNP adapters reboot reliably). The solution I have now is to put the 2.5 inch SSD on top of the case
, which is much simpler (same drive and JBTek case with top cover and fan installed).
Another option would be to mount the drive under the Pi
For a Pi0 solution, a tiny mSATA drive in an enclosure would be nice and compact.
My mind is like a browser. 27 tabs are open, 9 aren't responding,
lots of pop-ups...and where is that annoying music coming from?