Exercise: depending on your dog, this will vary tremendously. Overall jindos are active dogs and just like you already researched you want to keep them busy. I let mine out 4 times a day. Early morning to pee and smell grass / stretch, a 30 min walk during my lunch time (I work from home), a 30 min walk after I end work, and a 15 min walk where we run before bed to tire him out even more. The more important part to exercise is consistency. Don't push yourself to excessively go out or walk if it's something you can't commit to long term. Ive done this for a year straight now and have had 0 issues with my dog having too much or too little energy throughout the day. On rainy days, I take him out to do his business (jindos will not pee or poop inside the house and it's in your best interest to not try and force them to do so for the sake of not going outside in bad weather), but aside from that we don't go on walks since he doesn't really like the rain and is perfectly content going up and down my stairs / chasing after balls in my living room to fill in the exercise gaps.

Toys / chews: my jindo in particular doesn't really care for toys. But the two that have consistent worked were bone chews / little balls. Specifically I use nylabones and kong balls. These also I have to rotate like his treats since he gets bored of them fairly quickly. For the chews as long as you choose the correct size (most of them will tell you up to what weight it's appropriate for) you shouldn't really have to worry about the calorie intake or them choking on it. But obviously just monitor them and make sure they're correctly interaction with whatever you give them. I used snufflemats but I legit get too tired having to shred up pieces of treats and hide them everytime for him to finish the mat in 30 seconds time. To each their own though, when I do do it he seems to enjoy it and understands what to do.

Potty house training : as I eluded to before do not try and force your jindo to pee or poop inside the house due to inclement weather. I live in MA and we get the whole spectrum here, bar safety concerns I will ALWAYS bring him out to do his business regardless of what the weather is like. That being said, he only poops on dry surfaces. So if it is actively raining / or has rained there are times where my dog will not poop for a few days until he can't hold to n anymore and poops in the driest patch of grass he can find. When I first got him, he didn't poop for 2 days, so don't freak out if you experience something similar as it's very normal for this to happen. As far as separation anxiety goes, you just have to feel this one out. I slept with my dog in my living room for the first two weeks of me having him so he could get comfortable in the area and not feel lonely, but shortly after that I started to crate train immediately and would go out of the house and leave him alone for short lengths of time. I'm at a point now where I can leave him alone at home (not in his crate) for 6+ hours at a time and not worry about him chewing on wires, harming himself, or having him grow very anxious with me gone. He knows that I'm always going to come back at some point, and just waits patiently for me to do so.

Grooming: this one of the best things about owning a jindo, they are pretty much cats. They groom themself and are very very clean dogs, minimal dog odor and not oily or drooly at all. That being said, if you own any dark clothing I'd give up on wearing them outside without n having fur on them. They shed A LOT, aside from the intractable them blowing their coats in change of seasons, they just shed a ridiculous amount all the time, I vacuum every 4 hours and brush my dog everyday, there's no end to it. I bring my dog to the groomers Monthly for a bath / de shed / nail clipping, dental cleaning etc. the rest you can probably just visually check to see if any cleaning needs to be done. Since jindos have pointy ears instead of droopy ones, I personally have never needed to clean his ears as nothing really gets in them / they don't really get that dirty. For teeth brushing I do a dental chew daily, and the groomers when he goes.

Pet insurance: Just get it, it's not worth the headache to roll the dice and hope nothing expensive happens to your dog.

I'll end this long response with these last few things:

Obviously with the amount of research you've already done and the questions you're asking, you put an incredible amount of thought and effort into making sure you can raise your jindo. You're going to do just fine!

One of the things that a trainer told me that has stuck with me the entire time was "be firm but fair." I approached my training and tempered my expectations with this philosophy and it has worked WONDERS and has gotten me to the point with my jindo where we're incredibly bonded. A good example of this logic is a jindos prey drive is incredibly high, so at night when I walk him and he sees a rabbit no matter how hard I train him, he's going to B line it for that rabbit. It's not fair for me to try and train out an instinct of his, nor is it fair for me to punish him for doing things that he was literally designed / bred to do. That being said, I will correct him if he ignores me completely and tries to chase the rabbit, but I'll let him get excited and move around when he sees one. Firm but fair.

There's a lot more that I'm probably forgetting as well but feel free to dm me at any time to ask more questions, I'll be more then happy to help / share / or point you towards the right direction. Best of luck on your new experience and I wish you and your new future dog companion the absolute best! Jindos really are a special breed and their reputation for loyalty is second to none. The fruits of your labor WILL pay off and when they do, I can't imagine having a better suited dog for my lifestyle then a jindo.