Verdon Gorge

I hiked the Verdon Gorge with a guide some 20 years ago. There were parts of the hike that were quite technical (e.g., metal ladders). Parts of the hike were steep with loose rocks. The trail that I took would not have been appropriate for young kids. I would check trail guides to see if there are any trails that are appropriate for kids. The canoe might be possible, but I’d check with the outfitters directly to see if there is a minimum age.

Moustiers Sainte Marie is quite compact so I would think a 5 and 6 year old would be able to walk.

The start of the Couloir Samson hike is passable with children; access is via stairs rather than ladders. See this google maps link for some photos. You can park down a minor road below Point Sublime. You will need a flashlight, a smartphone will do. There are some cool views of the gorge between the tunnel bits, at some point the going gets more difficult but you can turn around.

If that sounds too involved, the short hike to Point Sublime is very easy (basically paved) and the views are, well, sublime.
And you can have some exceptional views driving along the Route des Cretes one-way loop from La Palud and stopping at the various viewpoints (Trescaire, l'Escalès and other viewpoints). Actually, if you only have time for one thing, skip Point Sublime and stick with the Route des Crêtes.

As for Moustiers: not very stroller-friendly but it is doable, the streets are partly cobblestone and some are steep. Park at the higher lot, if possible.