Not sure why you're getting downvited, people seem to have missed your clever use of the Cyrillic "o".

Why is the Cyrillic "o" even a separate glyph/charcode, even though it looks like a regular "o"?

Probably because it is rotated 360°.

Because it looks like an "o" in Verdana, but it could look different than the "o" in an other font.

Would it be possible to register a .xn--cm-fmc TLD and have a .cоm registry all of your own?

Stupid question, how did you do that? What characters are you using?

I frequently have to deal with lots of scientific, mathematical, and many other unusual characters.

I use http://unicode-table.com to help figure out what's what. The official Unicode specifications[1] is impenetrable, and it's really hard to deal with.

[1] http://www.unicode.org/Public/UCD/latest/

Second "o" is in fact Cyrillic "о" which looks indistinguishable from Latin "o" (unless you use some weird font without Cyrillic letters).

I think, it's impossible to register this domain.

Considering it's already registered, I'd say it's possible:

https://whois.domaintools.com/xn--gogle-kye.com

Thanks, I was wrong. That's even worse than I thought.

It looks like Google got all lookalikes, because I just tried with a Greek ο and that's also registered by them.