That's an interesting question. Most people acheive some level of ketosis at around 50g CHO per day or less. Some people have to go lower - down to 20-25g CHO per day. The amount of fruit you specify is only ~12g, so it should be fine. Unless, you are adding sweet potato/rice etc. I would personally eat the berries later in the day, when my blood sugar is lower, but that's me. And I'm not eating many berries right now.

Coffee, tea, dark chocolate, green tea and red wine all have interesting chemicals, some of which are antioxidants (or perhaps oxidants that invoke an antioxidant reponse from the mitochondria). I wouldn't say that they are better than the berries, but could complement them nicely. But it all depends on what you want/like - and if you like berries for breakfast, I say go for it!

(Although some fat and protein are useful, especially at breakfast, especially if you are struggling with weight - and I assume you are, unless the ketosis is for another purpose like brain function...)

For me a few berries didn't stop me. Especially with the inclusion of coconut oil. Don't forget that if your goal is to be in ketosis protein can be problematic. You want adequate protein, not high protein.