I hope everyone is healthy and safe.
I have one lvm luks encrypted ssd let's call it "A" and it is the main drive inside the laptop, and one lvm luks encrypted ssd on USB let's call it "B".
"A" boots no problem and I can access "B" on USB when "A" is booted up after issuing vgrename new_name and de-crypting "B"
However, I need to be able to switch these each out - "B" as main and "A" on USB for transferring files between the two.
If I take "A" out of internal slot and put in "B", the laptop does not boot, but will if I replace it with "A".
I'm wondering if some fancy grub commands can make this work and also wondering if I can make this happen automatically depending on which ssd occupies the laptop's main slot.
"B" has a fully functional Ubuntu 20.04 system but is unable to boot after "A" occupied main laptop ssd slot.
Thank you and any help much appreciated.
SOLVED: with help from the knowledgeable folks at linuxquestions.org, who pointed me to a very useful StackExchange solution: so indeed, all roads do lead to StackExchange.
https://unix.stackexchange.com/questions/445652/how-to-mount-and-de-encrypt-a-luks-encrypted-partition-to-recover-files