I'm in the same boat as you. Given that the second slot is only 2230 you're going to have a **bleep** of a time finding an ssd that fits. 2230 is generally reserved for wifi cards and such. 2246 is about the smallest ssd being made today.

The only manufacturer claiming to make 2230 ssd is Toshiba, model BG3 up to 512GB, in SED  (self encrypted) and non-SED versions.

https://business.toshiba-memory.com/en-us/product/storage-products/client-ssd/bg3.html

All I could find to buy is the deprecated 256GB BG1 model at some random site for $2700 USD. 

Please report back if you manage to find a reasonably priced 2230 ssd. Otherwise, your best bet is to swap out the primary ssd. Good luck!

How did you manage to get 2280  SSD into a 2230 slot? I am curious about this? As far as booting you might have to change the boot using F12 (spam the F12 key) on a Re-start or cold start from off. and select your 512GB SSD although your 970 should be RAW not activated or formatted so the boot manager wouldn't see it as  a boot device, you should have booted normally.

Yea that sounds a bit pricey, I wonder though are we really limited by 1TB M.2 SSD and what that limitation actually is? Would it be in the available space thickness-wise or something they have put into the BIOS to prevent 2TB M.2 SSD's? I mean we already have the right length and width 2280  so logically that only leave thickness single sided chips or double-sided chips pretty sure Samsung makes all there with chips on the upside. 

Anyway, I'm going to have to change out the current SSD it very slow and very slow booting 45 Seconds plus seems to me like something is not quite right about this SSD, I'm used to 15 - 20-sec boots with the same configuration actually this one isn't completely configured yet. Mistake on my part buying it with the add-on 512GB over the 256GB What was I thinking LOL

Make sure that in the BIOS Windows Boot Manager is the first boot option. If you still cannot boot from the drive with the OS on it try this. This time remove the 2280 new drive. If the system boots properly then shut down the system and reinsert the 2280 drive. If that does not help it is possible that the BIOS is still looking for Windows where the 2230 drive was located originally. Remove the CMOS (coin cell) battery and leave it out for 15 minutes (Intel recommends 30).  Then reinstall the battery and try booting again.

Before you do that though, if at the Dell splash screen you start tapping F12 and access the boot menu, can you select the 2230 drive and does the system boot properly from it (remember Windows Boot Manager)?

Not sure about any bracket, but the screw that holds the card in place can be purchased on Amazon. I haven't looked in mine yet but I assume there might be some sort of heat sink probably aluminum and stuck on the Card with .5 Thermal Pad. I'm shooting blind here I have never been inside this model, however, M.2 slots are an  industry standard and looking in the service manual 

Ok, So today I got my Samsung 970 EVO NVME, opening up my notebook I found a great surprise. I didn't actually waste my money upgrading from 256GB SSD to 512GB SSD, the installed 512GB SSD was installed in the 2280 Slot but it is a 2230 size SSD, So I move it to the 2nd SSD slot 2230 and installed the 970 EVO in the 1st slot I did have to move a bracket  back to the 2280 position the 2230 slot already had the bracket holder installed so no issues there. So I used Macrium Reflect to clone the 512GB to the 1 TB EVO moved all the extra partition in front of C drive and left 600 GB of unused space. This happens as expected in less than 15 minutes 20 minutes if you count the time sorting out what was what in the notebook first time opening it for me. So this all Works out great for my situation I am using the 512GB as D Documents, created two more partitions on the 1TB and Created E Consulting and F Storage. I have everything set up as I did on my Asus G752VY

Samsung 970 NVME 1 TB SSDDisk ManagamentDell supplied 512GB NNME SSD