The first pic shows the slashed 0, which is what I'd expect if there's any chance of confusion.

But in general, aviation is pretty paranoid over this stuff.

I don't know how this font is encoded, but it's often the case in modern fonts that variant glyphs are mapped to the same code point (i.e. U+0030 in this case) so you can't directly type the variants. If you want to use them then your software needs to understand how to select font features.

In CSS you can use font-feature-settings.

https://developer.mozilla.org/en-US/docs/Web/CSS/@font-face/...

It's confusing and certainly non-standard, but rather than using a variant for this, the slashed zero is U+E007, in a private use area.

There seems to be an unofficial variant here that might be more useful for coding: https://github.com/carlosedp/b612