Dual Boot from Two different disks BOTH with ONLY Linux

Solution 1:

Setup should be like any other OS combination. Install the OS on one disk, then go through the installation again but select the other disk.

Obviously the same OS would be listed twice in the grub menu, see How to safely change OS name in grub boot menu? for how to specify the name for each one. It has several viable solutions, I think this one is best for your setup. Edit /etc/default/grub with this change:

# GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_DISTRIBUTOR=`{ printf Work && lsb_release -d -s ; } 2> /dev/null || echo Debian`

This appends 'Work' to the OS, you can name the other OS 'Personal' too. Then update grub

sudo update-grub

For security, make sure you encrypt the work disk, otherwise you will still be able to easily access it from the personal one if it is compromised.

For potential issues, it's possible grub could get installed on each disk, where grub on the main disk doesn't see the second OS. That would just need grub reconfigured, or switch the default disk.