For a cat, loyalty is as strong as the bond they form with their human and that bond is based on trust. Trust they’ll be safe, sheltered, comfortable, fed, paid attention to, played with have a routine and interesting things will happen
From what I've seen cats are as loyal as dogs are. They are restricted by their size, they will fight to rescue their people, but a German Shepherd will be able to frighten a burglar with greater ease. This doesn't mean the cat won't damage the invader. However, it's best they hide and stay out of the way, because since you return their loyalty you don't want the burglar to hurt them.
From my perspective, it depends on the cat. Some cats are loyal to the bone, especially some breeds. Others would gladly turn you in for that extra hit of Catnip.
You know the funny thing is mine hates salmon and tuna and no longer cares for cat nip lol but if it’s like treats like temptations she will love some lol espically those kitty cat Lolipops she will purr while licking on lol
My Bengals that I have had have been loyal to the extreme...Blue that I have now when i return from work or being out demands a sniff inspection of hands feet and clothes before going zoomies in excitement of me being home. One time when I come home from hospital he climbed all over me inspecting and pulled off every blood test bandaid then sat and stared in my face for ages. They are a loyal breed to extreme..once they decide you are theirs thats it..all over!!
Mine were moggies, bred from their own desire and chance. But, they tended to put themselves between us and danger. Maybe it was curiosity, but they would get between us and dogs who got on the porch, and leap into windows at night when there was gun fire in the neighbor and watch. When strangers came to the door, they growled and took positions under the living room furniture. So protective, if nothing else.
Once we got dogs, they would go and get the dogs when there was the above sort of danger. After all, cats do know that size matters in a fight.
Some were good at nursing, being with you all the time you were sick. This was something that the youngest had to learn, didn't seem to come naturally, so I think, like human children, they didn't understand what illness was.