I come from a Scottish island (not Orkney) and tbh most locals are not big into non-locals moving in, especially when they're moving in to play out some kind of fantasy of island life. If you keep those kinds of notions to yourself, you might do ok, voice them loudly and in public and many people will write you off as a bit annoying. (I'm not saying you're annoying, but that's how it comes off sometimes.)
Also, people moving in is driving up housing prices massively so that locals can't afford to live there, so tbh, there is a bit of resentment.
It's not off-grid. Some places might use gennies etc, but that doesn't make it off-grid. And while that kind of thing may seem quaint and humble and fun from the outside, when you're sitting in the dark with no heat because there was a storm and the generator failed, it is just a bit shit.
I doubt your kids would thank you either, I hated being so far away from the rest of the world when I was a teenager. As a young kid, it was ok, but once I hit 13, it was so unbelievable to me that we lived a boat ride from anywhere. And that was as a local, uprooting them would make it worse imo. No possibility to make friends outside school in a small place either, so if your kids don't fit in, it's harder on them.
It's really beautiful, definitely. The locals will do anything for you once you're accepted. But I wouldn't do it without a lot of thought. If you own a house, I'd possibly look at renting that out for 6 months to a year or something, give it a go and pack it in if you don't like it.
I don't want to piss on your bonfire, but just seen so many people with the same idea move and ending up hating it.