If he's a teen and his only issues are visual (i.e. developmentally he's competent), the worst thing you can do is find a solution outside of the normal. Specialist equipment is overpriced, underpowered and generally a pain, at least here in the UK. The worst thing that holds the young people I support back is their parental worries.

There's a great thread from a few days ago on cutting specifically at https://www.reddit.com/r/Blind/comments/ou2tjd/strategies_for_cutting_food/
And products like manual mini food choppers, whilst incredibly sharp, are huge timesavers in the kitchen.

TLDR, a knife is sharp whether you can see or not.

Cooking is a vital life skill for independence.

The biggest safety issue is chopping with a knife. Use a "claw" grip with your hand so that the thumbnail/fingernails are all parallel to the blade, then line the blade up with your nails and cut downwards. See this video: https://www.youtube.com/watch?v=wVJUD8SSQRA

We teach our students to do all their prep work on a large cafeteria tray (e.g. put the cutting board on a piece of shelf liner (so it doesn't slide around) on a cafeteria tray) - this way all the chopping debris ends up on the tray, any tools they use stay on the tray, the mess stays on the tray, so at end of session you take the tray to the sink and should not have a mess on the counter. This works very well with the "Mise en place" (everything in place and ready to go *before* you start cooking (mentioned by brimstone_tea).

You can mark the microwave +30 second button or the oven knobs with tactile markers "bump dots" or the felt bumpers from cabinet doors to make these appliance usable.

There are a great number of tactile / low vision cooking tools at www.maxiaids.com and www.lssproducts.com - but I agree with the other poster in trying to use normal equipment first - he may not always have the other equipment but will have his skills and his senses. Some things are gimmicky and not worth the money, but YMMV. For example, this is a $5 disc (not vision specific) that can help prevent a pot from boiling over and makes a racket when a pot starts to boil.
https://www.amazon.com/JBK-Pottery-10175-Design-Ceramic/dp/B001PUMK98

Don't forget little appliances like the small George Foreman grills (great for simple sandwiches / burgers) or a simple crockpot (with just a basic control knob, no buttons). You want to look for appliances that are knobs or "one touch" operation - e.g. a $17 nofrills rice cooker (which can be used for far more than just rice - and is much easier than using the stovetop) with one button operation would be a lot easier for someone with vision issues than an $100 InstantPot (has lots of buttons and digital displays and requires good vision to use).

I would also say to get something like an Amazon Echo (or Google Home) for the kitchen. Being able to say "Alexa, set a timer for eight minutes" when your hands are covered in raw chicken bits is well worth the $45.

Sorry for bad english, my kitchen vocabulary is non existant haha.
I learned it the way that you put your index finger where you want to cut, slowly(!) Put the knife in front of your finger and then cut.
A few things I learned in training I found very helpful:
- remember that hearing things is very important, so no music, no extractor, no conversations so they can hear if the water is boiling or if the pan is ready
- at the beginning, gather _all_ things you need, ingredients, spices, measuring cups, spoons, spatulas... In one specific place and put everything back as soon as you've used it. This way your grandson will be able to find what he needs in no time
- have the handles of your pans facing the wall, not outwards where he could walk by
- when stirring, have him hold onto the handle while simultaneously stirring with the other hand
That's all I can remember now. Good luck 😃

Looks like you’re in the US? Have you reached out to your state’s rehabilitation services? A VRT can teach him safe cooking skills.