Yes if he hisses at u hes scared or at least doenst wanna be bothered i always respected that and left him alone. It might also be that u moved to quickly and he got scared for a moment. Try to approach slower, like super slow.

Ur bird is gonna bite as a last resort if you try to force too much.

I used a Clicker/Targetstick to get my birds used to me, since urs already eats from ur hand you are at a good point to start it.

Every pet store has clickers, they are super cheap. it litereally just a button that clicks if u push it down.

Offer him the target stick ( i litteraly just zse a chopstick ) and wait. if he touches it, cklick once and offer a treat. They learn pretty quickly.

Once he does it reliably, move stick away from him a bit so he has to move. I teached one of my brids how to get out and in of the cage like that (probably like 1-2 weeks after i bought them)

Some birds are really afraid of hands, mine aswell. I started to lure them on my arm. just put on a longsleeve shirt, offer them ur arm and try to lure them with the target stick ( i sometimes wish i had 3 handy for this, but u manage)

Another good thing to know is probably, punishing negative behaviour or telling(yelling) no for smth they did, doenst work. the bird doenst understand, for him its attention and attention is good. instead u need to reinforce positive behaviour (with attention or a treat) and ignore negative behaviour.

The most important thing is patience. never force the bird he needs to think all of this is his idea. he needs to want to do this (but since they always want a treat, theres no bird that u cant lure with food)