I brought a Nintendo Switch with me from Europe to Japan and back again, and never noticed any problems.
Electrically speaking, the Nintendo Switch should work all over the world. While it is charged over USB, I've seen reports about incompatibilities with certain USB chargers (I haven't encountered any problems so far), so you should either buy the official charger from Nintendo, or do research beforehand.
The official charger from Nintendo, which is shipped with the Nintendo Switch (all models) supports:
- Current: Alternating (AC)
- Voltage: 100 - 240 V
- Frequency: 50/60 Hz
Which should cover the entire world, unless there are places that use DC power instead of AC (Quora says there aren't). Of course, let's also not forget that different countries have different mains plugs, so you'll either need an adapter or buy a charger in said countries.
As far as software is concerned, the Nintendo Switch is not region locked (with one exception). According to Nintendo Support (America):
Are Nintendo Switch game cards region-locked?
With the exception of systems and game cards distributed in the Chinese region, Nintendo Switch game cards are not region locked.
Can Nintendo Switch play games from a different region?
Although Nintendo Switch software sold in regions outside of the Americas may work with Nintendo Switch systems sold in the Americas, we have not tested all overseas software with systems from all regions and cannot guarantee full service and support. Therefore, we recommend that players purchase software that is specifically made for their Nintendo Switch system's region.
Can I use Nintendo Switch in another country/region?
Although it may be possible, there are different factors to consider such as voltage requirements, wireless communication requirements, warranty coverage, etc. To ensure proper performance, service and support, Nintendo recommends using the Nintendo Switch console in the country where it was purchased.
Can I use accessories purchased overseas?
Although some accessories may work, we cannot ensure compatibility between systems and accessories for all regions.
To ensure proper service and support, Nintendo recommends using Nintendo Switch licensed accessories in the same country where they were purchased.
Use of unlicensed accessories may void the system's limited warranty.
In other words: There is no reason why you can't use your Nintendo Switch worldwide, but Nintendo can't guarantee it will always work since they didn't test it.
I myself have bought a Japanese Switch game (with accessory) and have had no problems playing it (including using the USB accessory). Additionally, in order to redeem DLCs for the game, I had to create a Japanese Nintendo account, which also worked. The only downside being that I now receive news from multiple regions, with no way to disable news from one region or another.
This brings us to the Nintendo eShop. While you can visit the eShop from almost any region:
Also note that the Nintendo eShop for the Chinese region is not compatible with systems distributed in the Americas.
... the region is determined by the one you set when you created your account. You can create multiple accounts from multiple regions, but the Nintendo Switch supports up to 8 accounts per console.
Keep in mind that anything related to the eShop itself is (in a sense) region locked. While there is nothing stopping you from using a Japanese eShop account outside of Japan (though the same does not appear to be true for Chinese eShop accounts), any DLC you can download from it is only compatible with games bought in Japan or bought through the Japanese eShop. Also, prepaid cards for games, DLCs, or eShop funds can only be redeemed in an eShop of the same region.
Can I use a Nintendo eShop prepaid card from another country or region on my system?
Nintendo eShop cards are compatible only for the Nintendo eShop country or region where they were intended to be sold. If you purchased a Nintendo eShop prepaid card for a different country or region, we cannot replace it, exchange it, or offer a refund.
Can DLC for one region be used with the same software title from another region?
DLC will work with games that are released for the same region as the DLC.
Thus I recommend creating an account for the region of your permanent residence and buying your games digitally on the eShop, unless there is a game you absolutely want that can't be bought in your region of residence, or you find a really good deal. Keep in mind that you can change your region of residence, if needed:
Please note that your Nintendo eShop account balance does not carry over if you change your Nintendo Account country.
Also note that the warranty is only valid in the region the console was bought in:
Can I get my system serviced under warranty in another country/region?
No, the limited warranty is applicable only within the country/region where the system was intended to be sold.