It’ll be best to buy in Taiwan.
You’ll need to check with the carrier, presuming you want to use cellular. It’s not the local model, and does have differences.
The warranty is also not international.
Some other issues that can arise here—and you know the recipients best—can be folks needing to don and doff the watch for its daily recharging, and being able to use and understand the display, to even be able to see the display, among other details. Pairing with a local iPhone, too. Some of the seniors I deal with are gadget savvy, and others are not, and all can have other interests and focuses. Again, you know your recipients here best, of course.