Anecdotally, it sounds like it's more likely to come up in Scouting than Guiding. I'm a leader for ages 10-17 and among, say, 16-24 year olds, it's not at all unusual to meet people who are gender non-confirming with brightly coloured hair, pronoun badges and 'known as' names.
These young people quite often seem to be autistic - they have non-typical affects and seem to thrive on side-by-side social interactions which follow a set of formal rules. Scouting is very welcoming and it's home for them.
Scout safeguarding rules generally keep things on an even keel. Adults aged 18+ must follow adult rules in their interactions with children. Everyone must be offered privacy to change, but mixed-sex tents are permitted if appropriately risk-assessed. In reality, it would be a cold day in hell before any of the groups I'm with allowed mixed-sex tents.
I have, however, run into problems with showers and washrooms; only theoretically, I hasten to add, and not in practice. For example, I've received instructions that leaders should let kids know which washroom they should use - rather than stipulating single-sex washrooms. I asked for clarification but received no reply. I like Scouting, and nothing untoward happened, so I didn't push it. It doesn't feel fantastic, though. And with the SC judgement, I'd be more inclined to try again to get a response.