Okay I just did a bit more research and have to correct/add to my first post. You can store special characters in DataStore by using string.char(unicode point), but it still won’t necessarily help you in saving data because special characters can be more than 1 byte.
I would not worry at all about trying to save space. If you are worried about the write limits I would recommend ProfileService which is an op module that pretty much takes care of all DataStore stuff and you never have to worry about it.