Nobody said it was canon. Novels aren't canon, they never were and they will never be, even if they are illustrate by Kishi.
It's canon if it happens.
Sarada will activate her 3T in the manga for the first time anytime soon. That makes her having 3T canon.
The difference between Sasuke shinden and the field trip novel is that field trip novel doesn't have Kishi's involvement at all, and it actually came out after the arc on the anime, in other words, the novel "covered" something that had already happened.
Sasuke's Shinden only states that Sarada has a 3T, but it doesn't mention how she got it. It's untapped territory for the anime to cover - unlike the field trip.
Sarada will use Medical ninjutsu. Nothing points the contrary.
She won't. There are no indications whatsoever that she ever will.
As I said, she spent her entire life with Sakura and all she knows how to do is to put on some band aids. Sakura is the best medic nin alive and Sarada is her daughter. Pretty sure that if Sarada was interested in learning medical ninjutsu, she would have learned it at this point.
She spent 2 or 3 days with Sasuke, asked him to teach it, and learned how to Uchiha fireball.
this doesn't mean she will be a medical nin, no need to worry.
Agreed. It's pretty clear that she won't be a medic. But I doubt she'll use medical ninjutsu.
so, novels aren't canon now.
ot: Not a surpirse her mother is sakura afterall, that would be pretty stupid for her not to pick up something up from her.
Mitsuki canonically has it in the Boruto manga DB. Not in a novel.