Ronen, I think the keyword of both verses is "can".
The two main meanings are:
1] Have the ability to do something.
Being able to lift an object.
Have enough money to buy a car.
Be able to win a fight.
2] It's legally/morally allowed to do something.
Many things usually are physically possible but a can't be done be cause of certain consequences.
Most people can take 4 hour lunch breaks but at the same time can't because they will get fired.
Most people can hit a judge but at the same time can't because of the legal consequences.
The plumber that fixed your sink can do it for free but at the same time not because he will get fired.
Obviously when reading a text it's not always clear which meaning of "can" is used.
'I can't shoot the president'
That can't mean so many things. Too much security. It's against my moral values. I never learned to shoot. I'm blind. Etc.
The way I read the two verses you quoted strongly leans toward definition 2.
Jesus takes Father's actions as His moral guide as His law. He copies Father's personality.
Jesus had free will but look how He used that free will.
v19. He looks what Father does and does what He saw.
v30. He listen what the Father says and that the (basis of) the judgment He makes.
He could have done otherwise
v19 He could not look and do whatever He feel is best.
v30 He could seek His own will.
But it's never that easy....
If we say that Yeshua could do nothing of himself (which is different than saying he chose to do nothing of himself, if that were even possible),
I think both apply to Jesus at the same time. It's may sound like a little paradox but it's isn't that hard to understand.
He did chose to do what Father did, but at the same time He can't chose at all because not doing so would conflict His own moral standards.
Most people 'function' at least in part that way. Sometimes people look at the law when doing things. Sometimes they follow their own moral standards which just happen to be the law also.
Many people like speeding but they don't because of fines. They look what the law says. (look what Father does)
--> Written law. Checking what others have to say about it.
Most people don't torture babies. They don't even bother to check what the law says on this matter. While they physically can torture a baby their personality is 100% effective stopping the person to do such things. So they made their own free choice because they didn't follow the law (looked at Father) but listened at their moral compass which just happened to align with the law.
But where does that moral law comes from? I think it's a combination of many things but for simplicity I'll only use parents in my example. Parents teach according to their own moral standards which covers many area's of life including things like social behavior (which often are law derived from laws), political views, laws, etc. Those things form a personality. That personality is the engine of free will. So my free will is largely made of my parents moral standards. So my free will is at least partly that of my parents.
--> My free will is the law written on my heart (by my parents, society and laws of my country)