Deleted my answser since I believe I found the correct answer.
Found this website that list all the SSD Compatibility List for Laptops: https://laptopmedia.com/series/acer-nitro-5-an515-42/
Now if you install the M.2 NVME SSD and the laptop doesn't recognize it, most likely the problem is that the NVME you purchased is not compatible with the laptop. So will need to make sure the M.2 NVME SSD you buy is compatible with your Acer Laptop so that it will be recognized.
That depends on your Laptop's Motherboard whether its M.2 slot support NVME or SATA or both types of SSDs.
"M2 Slots have keys called as M key and B Key to differentiate between support for NVME and SATA storage drives.
- M Key is only for a PCIe/ NVME storage Device and a M + B Key is for a SATA storage device. If you look at your M2 interface on your Motherboard and you see a single notch ONLY for the M Key, then it will support both NVME and SATA M2 drives.
- Otherwise,If you see a notch for BOTH the M + B Key then it a SATA SSD storage Only slot. Again this is inferred by looking at the board NOT the SSD Drive itself as a NVMe will be M key only while a SATA Device will have both but it all depends on what the type M2 slot /connector the motherboard is provisioned with.
- Check if your M2 slot corresponds to the two Keyed slots for either NVME or SATA SSD by using the following figures of the two type of SSD’s ."
All of the above are from 3 different sources.
This YouTube Video is showing how to install a M.2 SATA SSD in your Acer Model: The one in the video is a 250GB SATA SSD Western Digital. It has 2 keys on that SSD: https://www.youtube.com/watch?v=I_NFBwQw7zM
 
 
 
 
It has single notch ONLY but other community members saying that they tried NVMe M.2 SSD but it didn't work for them. We're using latest version 1.18 of BIOS when we talked about this issue with Acer Customer Service they told us that maybe NVMe not working because of some motherboard issue.
The thing is I'm not understanding why they (ACER) put slot which has only single notch & looks like NVMe but didn't support NVMe. Also they're more confused than us when we're asking for help from then.
Deleted my answser since I believe I found the correct answer.
Found this website that list all the SSD Compatibility List for Laptops: https://laptopmedia.com/series/acer-nitro-5-an515-42/
Now if you install the M.2 NVME SSD and the laptop doesn't recognize it, most likely the problem is that the NVME you purchased is not compatible with the laptop. So will need to make sure the M.2 NVME SSD you buy is compatible with your Acer Laptop so that it will be recognized.
