I learnt to the play the flute as a teenager. I want to play for children. My hands weren't great in dexterity as a teenager and probably a bit worse. I haven't played for 10 years. I live in Japan and while there are music shops, they aren't great. What should I consider when choosing a flute whether in person or online?
My first piece of advice is play as many as you can get your hands on. This may involve some travel.
Next, think about how much you're thinking you're going to spend on this instrument, then about double it or so. Unless you're already familiar with what instruments cost, there's often a fair amount of sticker shock involved with buying a horn.
The next thing to consider would be brand. I don't know if Japan has an equivalent, but in the US there's the National Association of Band Instrument Repair Technicians (NAPBIRT). If you can find someone that is associated with them, you can get their opinion on good instrument brands. One word of caution: a lot of people will tell you that anything that comes out of China is garbage. They have good reason to do so: that used to be true. See the end of my post. The reason I tell you to seek out a repair technician is that, while a particular instrument may sound good or be less expensive, if it's a bad instrument then there's a good chance that you won't find a respectable repair shop to fix it. I worked at a band instrument repair and sales shop for eight years, and when those sorts of instruments came in, the techs would put their hands behind their back, take one step away and say, "No," because the repair guarantee on them was "30 feet or 30 seconds", meaning they couldn't guarantee their work on them.
The next piece is to decide what level of instrument you want. You may currently only want to play for children, but that may change in the future, so perhaps an intermediate flute might be a better choice. Seek out an open-holed flute; don't worry about having to play it exactly right right away, they come with plugs to turn them into closed-hole flutes.
Beyond that, it's more or less up to you. You and I could play the exact same instrument set-up and get completely different sounds; that's because the biggest influencer on how you sound is you.
Okay, now that I've gotten all that out of the way:
Go buy a Di Zhao DZ-300. Yes, they come from China. Yes, I'm suggesting that you buy something without trying it first.
The owner of the band instrument store where I worked used to be the president of NAPBIRT, so you can trust his opinion on instrument construction. When we started stocking these things, they started flying off the shelves. I worked there another 3 or 4 years after we first got them in, and we still sometimes had trouble keeping them on the shelves.
The DZ-300 is open-hole and it's got the B-foot, which is a somewhat advanced feature, but it's lower-intermediate instrument. Brand new it'll be around $600-$800 USD, but it'll sound like a flute that costs twice as much. I'm confident you won't be disappointed.
FINALLY, once you get a horn, go take at least a couple lessons with a private teacher. A few lessons at the beginning can help correct or prevent mistakes in technique that take years to break, if they even can at all.
Don't buy so cheap that the thing will impede your progress or fall apart after a few months. Notwithstanding the advice above to seriously look at Di Zhao (I've read many positive reviews), Japan has a thriving flute industry. Personally I've had good luck with Yamaha and Pearl. Jupiter too (I think they are from Japan). One feature to look for is offset G key because of a straighter left wrist angle puts less of a strain.