Not seeing his surroundings won't make him uneasy. Not seeing my surroundings very occasionally makes me uneasy, but then I had 19 years of totally normal sight to compare to. You'll get some responses from people who've never seen and don't really get that uneasiness, so I wouldn't be too concerned.

Chemotherapy is rough on anyone. I was around my dad when he did it (he's fine). All you can do is take medical advice and act accordingly. Chemo is a blunt instrument and it makes people feel rough. It'll be over at some point.

I guess what you're asking is whether you should be kind or pushy. I have a normal career that is nothing to do with being blind and my experience is helping out unofficially talking to people who have recently lost sight. The youngest was 14, so it may not be directly relevant but I'll tell you what I can. I alter my approach depending on the person but there is a reason they call me the drill instructor (mwahahah!)

Yes, I have been accused of having an uncompromising attitude but to speak plainly, your son is likely going to have a life in which he has to deal with a bunch of shit that most people don't. That is totally manageable, but your instinct that he will need some toughness is pretty accurate. There are certain things you will naturally do like making sure there's proper education stuff in place, mobility training and so on but at some point he has to survive in the real world, have a career, have a decent life. Special facilities are great but the world is not a special facility.

You walk the line between standing up for yourself, and being an abrasive activist. That can alienate otherwise helpful people and I am very cautious about it. The online echo chamber is really good at turning people into shouty disability politicians. It feels great in the short term, hey, I'm helping, I'm being an activist, listen to how loud I can shout, I don't think it leads to good long term outcomes.

In my view what you're trying for is friendly assertiveness, insisting with a smile on your face and in a way that's compatible with the real world. The other harsh reality is that people who have never seen (or not since they were very young) don't learn certain aspects of body language, fashion, turnout, etc. Some disabled people get fat and live in stained sweatpants which is obviously not going to contribute to glittering career opportunities regardless how well you can see or not. It's harder for those of us who have to wear makeup and heels, but shaving, shoe polish and spending a few hours a week in the gym matters. Fitness helps everything.

So yeah, kind but firm and definitely no coddling. The only person who will be available one hundred per cent of the time to help out your son is himself. We'll all keep trying to make the real world friendlier, and that's great, but... the real world doesn't care what we think!

I think that you should absolutely treat him the same way. As a sighted child. The only allowance is for different interest and different personality but not disability.

I think pushing him a little is fine, you can a 100% tell when someone whose visually impaired or blind have been kept in a bubble, it makes them more out of place than being disabled.
buy toys with different surface textures and play with him a bit with those, make it fun and then it could progress to "this is how the floor feels, this is a tree, grass, fur, rock," and so on it might make the outside world something fun to explore?

Does he respond to stimulation? Your 2-year-old is active because he can interact with the myriad of things that he sees. If you were to dangle a noisy toy just out of your younger son's reach, he should become interested in it. He has not developed the skill of thinking to look around for stimulation—if he can't perceive it, it doesn't exist.

You should make him have a variety of experiences.

Are you receiving early intervention services? Those professionals will have much better advice than we can give.