On UK layout ~ is next to the enter key and suffers the same problem as ?

On the Spanish layout, ~ is practically nonexistent. You can do it with AltGr+4 but it's not even visually shown in many keyboards (e.g. in mine). I know how to type it because I'm a programmer, but 99% of Spanish laypeople probably don't know that symbol can even be typed. So that wouldn't be a good choice.

On my UK keyboard version I just use the left shift with my little finger and press w with my middle finger, both on the left hand. Then use the right for the numpad as suggested. If I need to press ? I use left shift in the same way and hit the / key with my right hand. I don't personally see any issue with that, but if it affects others I guess it's important. In contrast though the ~ key is the shift version of # and is literally only one key farther up and right. It makes a difference but maybe not a large one. It's still useful, though.

"0" (zero) now also has been added. There now should be something for everyone ;-)