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Edit: I know sliding UPVC hinges usually have some degree of restriction on them anyway, but not sure if this could be adjusted down to only open, say, 3" without pressing the release catch.
https://www.homesecureshop.co.uk/products/upvc-window-restrictor-child-lock-restrictor-hook-safety-catch for a random aftermarket example. You should be able to have something factory fitted too.
That'd look nice but I don't think any of them would end up big enough to crawl out of in the event of a fire. Having actually done a Google I think I'll probably go for a big side guided with a fixed or top hinged top. The side guided (as opposed to hinged) will allow for cleaning. I'm assuming there exists some mechanism to stop a toddler opening up a window wide enough to crawl out of.
Edit: I know sliding UPVC hinges usually have some degree of restriction on them anyway, but not sure if this could be adjusted down to only open, say, 3" without pressing the release catch.