Can a multiclassed Dreams druid/Storm Herald barbarian activate their Tundra Storm Aura while in Wild Shape?

In my next campaign, I will be the solo healer, as a Circle of Dreams Druid.

I hope that will provide enough Goodberry and other healing skills to keep the party alive. But I really want to fight too. Because of that, I searched how can I be more supportive and be good in combat too. And I decided to multi-class with the Path of the Storm Herald barbarian. But now I am a little bit confused about whether I can always use Barbarian features as I thought.

I want to do some Tundra Storm Aura-raging while I am in my Wild Shape. Is that possible?

I need that feature to support my teammates with temp-HP while I am in the fight.

Can a Tundra Storm Herald Barbarian pre-emptively freeze the water of a Decanter of Endless Water?

Disclaimer : This question pertains to realizing a non-mechanical, very specific thing for goofy purposes. You may take it with a grain of salt.

A Tundra Storm Herald Barbarian (subclass from Xanathar’s Guide to Everything) gets the following Storm Soul secondary feature at 6th level :

Moreover, as an action, you can touch water and turn a 5-foot cube of it into ice, which melts after 1 minute. This action fails if a creature is in the cube.

Let’s assume that the secondary feature lets you make a smaller cube than 5 foot (if you have access to less water than that).

A Decanter of Endless Water is an uncommon Wondrous item magic item that lets you shoot water from it :

This stoppered flask sloshes when shaken, as if it contains water. The decanter weighs 2 pounds. You can use an action to remove the stopper and speak one of three command words, whereupon an amount of fresh water or salt water (your choice) pours out of the flask. The water stops pouring out at the start of your next turn. (goes on to list the three options)

The goal here is for the Tundra Barbarian to “shoot ice” instead of water (no added mechanical effect). To that effect, can a Tundra Barbarian pre-emptively freeze the water contained inside a Decanter of Endless Water (in order to shoot ice upon activating the Decanter) ? (for example, by removing the stopper without saying a command word, and reaching his hand inside the device to freeze water, which may or may not be possible)