I'm totally against an outdoor nursery. In the same way I'm totally against an indoor nursery. Free-flow and continuous provision is about giving children choice to decide how they want to learn. In an indoor only nursery a child who learns best outdoors is screwed. In an outdoor only nursery a child who learns best indoors is just as screwed. Have balance and give a choice.
I am in favour of a nursery where the outdoors is as valued as indoors. The outdoors is fantastic for learning. In my experience most people are interested in setting up outdoor nurseries on a cost basis. No building means cheap.
Parents tend to say they like the idea, but usually go on to say they'd maybe like to send their child for a morning a week or something. They tend to see it like a 'paint your own pottery' place. Somewhere to go for a session. Not daycare.
Your survey will almost certainly give rather skewed results. It you like the idea of keeping children outside all day you will go fill it in. If you don't like the idea, you won't. The result will be near 100% in favour of outdoor nurseries.
BTW I'm a bug catching, den making, veg growing, experienced and qualified nursery worker and gardener.