24-70mm f/2.8 lens -OR- Gimbal, external monitor mic, etc.?

Hi,

I'm thinking of upgrading my Nikon D7200 DSLR to a full-frame mirrorless camera in a month or two. I have been doing landscape photography and now want to embark on filmmaking/cinematography (travels) to document our experience in going to places subject of my landscape photography. So basically, I'll be doing landscape photography, travel filmmaking/cinematography, a little portraits, and family events. No professional work here (for now), just a beginner wanting to get into and stay in the hobby. 

I'm looking at a budget of U$ 3,300.00 aside from the proceeds of the sale of some of my existing equipment. With that, I would have either of these 2 options at the end of the day:

Nikon Z6 Filmmaker's Kit:
Nikon Z6 body
Nikkor Z 24-70mm f/4
Moza Air 2
Atomos Ninja V
Rode VideoMicPro+
Nikkor 50mm f/1.8g (existing lens)
Yongnuo flash (existing equipment)

-or-

Sony A7iii
Sony A7iii body
Sigma 24-70mm f/2.8
*Savings up to $1,000

with this, it's basically: 24-70mm f/2.8 lens vs. Moza Air 2, Atomos Ninja V, Rode VideoMic Pro+, 50mm f/1.8 lens, and flash.
and which system is somehow future proof for at least 3 more years?

My thoughts here:

1. If I choose Sony, I can still buy the Moza Air 2, and 50mm f/1.8 lens using the $1,000 savings, if I do really need them.
2. Nikon would be ok as I wouldn't need the f/2.8  aperture that much anyway. If I need one, I still have my existing 50mm f/1.8 lens.
3. I don't see how the Rode VideoMicPro+ would be useful to me. At least for now.

This is just me, a beginner in the hobby, thinking out loud. What are your thoughts on this? Would you choose the f/2.8 lens over the other equipment I mentioned?

Thanks in advance.

IMNSHO there's no such thing as "future proof".

You can expect to geth 3+ years out of your equipment, possibly more, depending upon what problems arise that need solving by newer equipment. You're a hobbyist, so I'll say "not many" to that.

Rule #1: it's not the camera.

If you want to learn to make films, there's a lot to learn, and you probably already know enough about the technical elements of the camera to be able to use any camera.

The Ninja is great, but you're going to need more storage for your computer, too.

As for lenses, that's up to you. What is your aesthetic? And is that 50 a DX or FX lens?

That said, Nikon. But I'm biased.

And you'll find the gimbal a useful tool, so that's probably a given for filmmaking.