With a cross, you have no guarantee of what the puppy will inherit.
So I would say no.
Also, most dogs are ‘loyal’ and about being a good guard dog, what are you defining as a guard dog exactly?
Because virtually all dogs will bark at an intruder.
When it comes to actual defence, as in protecting you from an attacker or taking on a burglar, you are highly unlikely to find that trait in a pet bred GSD, they don’t have the right mix of drives.
Even if you get a working bred one, that in theory should have the correct temperament for genuine protection, without specialist training they most likely, will not defend you.
To the poster that has always had shepherds and thinks it’s unfair to state their temperament is a mess.
I stand by that comment 100%.
Yes they are handler sensitive, all shepherds and collies tend to be.
But the proper GSD temperament has good solid nerves.
This has been largely lost in pet/show bred shepherds who are now largely either neurotic and hyper and fearful or super duper soft and friendly.