^ This. Also, check out the Godox V860III-N TTL Flash for Nikon since it feels safer.

• Li-ion battery lasts forever
• Physical TTL/Manual switch It's basically a reliable, budget-friendly tank.

Building on the earlier suggestion, Ive been extremely satisfied with the Godox TT685II-N TTL Flash for Nikon. Everyone loves the V1 but this model is a total workhorse that handles the Z6II TTL communication very well without that round-head price jump. Its a cost-effective choice that leaves plenty of room in your budget for a backup unit. Quick tip: definitely update the flash firmware immediately. Most of those TTL consistency issues people mention were fixed in recent software patches from Godox. Also, pairing it with Panasonic Eneloop Pro AA Rechargeable Batteries will ensure you get the fastest recycle times during the ceremony. I find this setup works well and I have no complaints about the performance during long wedding receptions. Its just a solid, logical path if you want to avoid the Nikon brand tax.

To add to the point above: I think the Godox talk is fine for hobbyists, but weddings are a different beast. In my experience over the years, the real reason to pay the Nikon tax is for the communication stability. When the Z6II is hunting for focus in a dark ballroom, native flashes like the Nikon SB-5000 AF Speedlight or even the slightly older Nikon SB-700 AF Speedlight just talk to the camera body more reliably. If the SB-5000 is too much for your $400 budget, you might want to look into the Nissin MG80 Pro for Nikon. It is built like a tank and has high heat tolerance, which is basically essential when things get fast. Ive tried many brands and always end up going back to Nikon or Nissin for paid gigs because I cant afford a flash freeze during the first dance. The TTL issues people mention with mirrorless usually happen because of how the pre-flash is metered. Nikons own system is just more refined for their sensors. Honestly, a used SB-700 is a safer bet for a wedding than a cheap new unit. It wont overheat as easily and the color stays consistent frame to frame... which saves you a ton of time in post-processing later. Stay safe and good luck in Chicago!

Can confirm

Great info, saved!

Honestly, I went through this exact same panic when I first got my Z6. I ended up grabbing the Godox V1-N Round Head Flash for Nikon because that $260 price tag was just way too tempting compared to the $600 you gotta drop for the Nikon SB-5000 AF Speedlight. Here is the thing tho... you really gotta be careful with the firmware. When I first took it to a wedding in a dimly lit ballroom last year, the TTL was kinda all over the place. I would get one perfect shot and then the next one would be totally blown out for no reason. It was super stressful while trying to capture the first dance and I almost lost my mind. I would suggest making sure you have the latest firmware installed before your Chicago gig because that fixed like 90 percent of my consistency issues. Even now, it is not quite as bulletproof as the native Nikon stuff but for the price difference? I think its worth the occasional tweak in post. Also, just a heads up, the hot shoe mount on the V1 can feel a little bit wobbly on the Z bodies sometimes so just make sure it is locked down tight. If you have the extra cash and absolutely cannot afford to miss a single frame, then sure, suck it up and get the Nikon. But for a $400 budget, I would suggest sticking with Godox and maybe getting the Godox XPro-N TTL Wireless Flash Trigger too so you can move the light off-camera if the venue ceiling is too high for bouncing.