I think this is a super idea.
I recently came home from a much needed holiday with my husband and was talking to my adult daughter about it. She's autistic, anxious but can do things with support systems in place.
She said to me 'I'd love to go mum, but I'd not cope without someone like you with me'.
A supported holiday rather than a constant companion on holiday would mean she could access holidays.
She'd need someone with her to guide her through the airport and flight, getting baggage and getting to a hotel.
Once there she'd need someone on hand to help with anxiety and show her where things were.
She'd need help to get to activities.
She'd need gentle reminding of times and places. For example when food was served and where.
But she's quite capable of repeating things once she's shown.
The difficulty is if she's not supported and has a meltdown then that the entire holiday is over for her. The amount of anxiety and mental energy expended would mean she'd need a week to recover.
But having been her 'person' for so long I know she can do this with support.
I think you'd need to be very skilled in asking and understanding the help each person needed. Putting this in place might take practice.
I always say she needs the guidance and support of a 9 year old but she's a young adult that can do some things herself.
My daughter loves Disney and would love to be able to go. Maybe Euro Disney? Flights would be easier.