How to ensure a stolen MacBook Pro Retina is useless to a thief? (There are similar questions to this, but they all are old, like OS X Snow Leopard old. This is for Catalina era.)

I carry my MacBook Pro on me almost always when I go places. I keep it in my backpack. While the threat of it being stolen doesn't loom too badly where I live, and I don't ever let it out of my reach, I still want to make sure that my Mac is useless to a thief if it is stolen.

Currently, I have FileVault 2 full-disk encryption enabled, as well as Find My Mac enabled to the full extent and I have a password set on the EFI to prevent booting from external volumes. 

How effective would this be, and is there anything I could do additionally to ensure they can't bypass these measures to use or sell the machine?
The security you’ve enabled probably won’t deter the theft of your laptop.  Most criminals who get the opportunity to snatch a laptop will take it no matter how useless you can make it with encryption and firmware locks.  

Why?


Ignorance of the criminal.  No matter how much Apple advertises it, the common thief won’t know until they get it back home only to find they got a brick.  Then it will probably become a frizbee.
Salvage value.  Although useless as a computer, the machine becomes a “donor” for the parts including the screen, trackpad, keyboard etc.  even the logic board can supply someone with a ton of components to be used in logic board repair


Your strategy should be data protection, ensuring that no matter where your computer ends up, you have quick, secure access to your work product.  Enabling remote wipe is invaluable in making sure your data stays secure.  

I would also look at insurance coverage for that expensive device.  Many credit cards cover theft.  There are also 3rd party insurance coverage from companies like Safeware