Not a device but a lot of norms: Digital everything. Even digital drivers licences. It's a norm to carry only a phone and keys in some parts of the world. Even payments have a different norm. The vending cart lady has tap and go payments and has done for over a decade now. When I moved to the USA I had to buy a wallet for the cards they use here. That was 5 years ago and the USA still isn't there yet.

Banking. Not a niche device but there's no need for Venmo or PayPal type apps in much of the world. The government mandates all banking system Apis and there's instant free transfers to other accounts. I just had to pay a $10 transaction fee for a bank transfer in the USA and it was a hassle (not done phone to phone but through routing and bsb numbers).

Taxation. It's a government integrated system. It still has a ton of special tax edge cases but for the most part you log in see your employers entered wages and tax paid and acknowledge. It's a much much better app than TurboTax and for the exceptions they are just checkboxes for meeting the criteria and fields for amount spent in the category etc. No TurboTax premium required since it's the government's app.

Universal public transit apps. You tap on the ferry with your phone and tap out of the train station later in your trip. It's all integrated.

In fact riffing on taxation why isn't there more done online. Why do I need to go to the DMV short of an in person driving test?

I'm not sure about specifics but when I was looking for android devices with small screens (like 3") last time, I found some indian smartphones. They were ultra-budget and I wanted something premium so I didn't pursue it further, but it was definitely something I never saw in the public market.

Another specific niche might be babushkaphones. It's a cell phone made for babushkas. Basically huge buttons, screen with huge fonts, dumbed down interface so people with very little technical knowledge could use them to be on line.

Well, Japan had plenty, including devices that integrate NFC for payment (before smartphones globally routinely have it) and built-in digital television receiver (while a lot of phones in Asia have analogue TV receivers, Japan's are usually digital in part because their digital TV format (1seg, https://en.wikipedia.org/wiki/1seg) have been developed with this in mind).

Not a specific device, but usage. In early-mid 2000s in Ukraine, most (if not all) cell phone services were prepaid, and special SMS or codes allowed you to send some amount of money from your account to someone else. Since not many people had actual banking accounts, this was a de-facto banking system at the time.

I believe this or similar systems are still in use in some countries.