Main sources: Change the sex designation on your government IDs, personal experience

(I live in Ontario now.)

In Ontario, government IDs (driver's licenses and photo cards) can have an F (female), M (male), or X (gender neutral) sex designation. ("Sex designation" is the language used by the province of Ontario, not my choice of words.)

Changing from an F to an M or vice versa requires either a birth certificate/registration with the correct sex or the standard doctor's note BS (which is also required to update Ontario birth registration and birth certificate). However, anyone can change to an X without any supporting documents.

Getting a driver's license with an X in the sex field is a little complicated, though. To apply for a driver's license, one must visit a DriveTest facility, but DriveTest can't issue licenses with X sex markers, only F or M. This record must then be updated at a ServiceOntario. (Apparently, you can also get an Ontario driver's license at the ServiceOntario Bay and College location in Toronto. As it's a ServiceOntario, I imagine it's possible to do the whole process there.)

Here's what the process looked like for me. (Note, I was exchanging an out-of-province license, not applying for a new one.)

1. I went to a DriveTest facility and waited in line.
2. I provided my passport as identification, my out-of-province driver's license to be exchanged, and an official record of my driving history. (This record is important, as you can only self-declare one year of driving experience, and you need 2+ years to get a full (G) license.)
3. I argued with the DriveTest employee about how long my driving record said I had been licensed. (I legally changed my name at some point in the past, and my driving record makes it sound like when I changed my name on my license, I was being issued my first driver's license.)
4. I was told that DriveTest could not enter my sex as X, and I would need to temporarily list a binary gender. I was allowed to self-report my choice of F or M because my identity document (my passport) lists an X for my sex field.
5. I did an eye test.
6. I filled out a form, provided my address and signature, and paid a $90 fee.
7. I was given a temporary paper driver's license to use until my plastic card arrives. The paper license has a binary sex marker.
8. (My passport was returned. My previous driver's license and driving record were kept.)
9. I went to a ServiceOntario facility.
10. I presented my temporary license and said I wanted to get an X gender marker on my license.
11. The employee didn't know how to process this request, so they called a different office and asked.
12. After learning what to do from the other office, the employee told me the sex marker in the system and on my temporary (paper) license needs to be binary, but they made some change and told me my plastic card would have an X.
13. They filled out the same form I had completed at the DriveTest and had me sign it. (There was no fee for the sex marker change.)

At the time of writing, I'm still waiting for my plastic driver's license card.

Update: I now have my license, and it has an X in the "Sex/Sexe" field.

Conclusions and thoughts

I'm glad getting an X gender marker is an option, but the process is ridiculous. It requires visiting two different facilities and selecting the wrong gender marker as one of the steps. It also sounds like you still show up everywhere with a binary gender except on the actual card. I've been assured that my driver's license will list my sex as "X", but all documents I've received so far (including the form I submitted to change the sex marker) list my sex with a binary marker. This does not inspire confidence.

Basically, my conclusion is: This process should be better. I thought it might be useful to talk about the process, though, so here we are.