Two weeks ago I've been in similar situation on an 80 gig sata drive.
Found it with 8 partition; boot was there but nothing of the operating system to load Linux 5.6
My recovery solution was to put the disk on a window system as a secondary drive. Just connected to read data For reading I found a software called ' nucleus kernel linux' from http://www.nucleustechnologies.com/Linux-Data-Recovery-Software.html
On partition 3 I found nearly all my data files and their directories but were missiing /etc /bin /dev ....
Hope this help.
--- Michel Donais