This is the difficult part. There are plenty of adults (who aren't sex offenders) who have transitioned a decade ago.
For example, I have a relative who transitioned from female to male, many years ago. Years of cross sex hormones, mastectomy and who knows what else. All documents changed to reflect male gender.
They present male. Full beard, etc. The executive order means they legally have to use female toilets. The risk now is getting beat up for using the toilet they legally are supposed to use.
No idea what happens regarding the passports, health insurance for hormones, etc.
There's no "third space" or solution for people who transitioned long ago.
While I'm in favour of protecting single-sex spaces and not indoctrinating children at school, I can't ignore the fact that real people will be hurt by this.