@farmerman,
I’ve no recommendation for your front door, but as for the barn, there’s a product generally used in marine environments that might work for you. I no longer have the product info and the guy who gave it to me is away this week so I can’t give you the name at this point (though I’ll ask this weekend when he’s back). I googled a bit but can’t find it.
For sure it comes in powdered form. I know that’s how he purchased it, though if memory serves, it can be bought premixed. I think. I tested some as a potential deck sealer last year (er, maybe the year before). It goes on a clear, watery consistency, dries clear and the wood initially looks untreated, but gradually weathers grey as it is exposed to sun and rain etc. just as you expect cedar to do. Supposedly lasts a life time, becoming stronger over time. Non toxic.
New wood looks so gorgeous and I can see the appeal for keeping it looking natural but I’d cry (or kill someone) if I had to paint a barn door every year. Even a clear stain would make me grumpy or worse. Apparently this stuff doesn’t need reapplication. It’s probably worth a look. I’ll try and get back to you.