Macbook pro 2015 13" Upgraded SSD not found

As I suspected you are booting to an older OS which does not support an NVMe SSD (hard to tell from the low resolution picture of the SSD, but it appears to say NVM express on the label). Beginning with macOS 10.13, Disk Utility now has a "View" option on the toolbar just above the left pane of Disk Utility. You can try booting into the online macOS 12.x installer by using Internet Recovery Mode using Command + Option + R. If that does not provide you with the Monterey installer, then you will need access to a Qualifying Mac so you can create a bootable macOS 10.13+ USB installer:

How to create a bootable installer for macOS - Apple Support

If the original SSD still boots, then reinstall it so you can create the bootable macOS USB 10.13+ USB installer, otherwise you will need access to another Qualifying Mac. A Qualifying Mac is one when is compatible with the OS installer you want to download. For example to download & create a macOS 10.13 USB installer you will need a Mac from 2010 to 2018 or to create a macOS 12.x USB installer you need a Mac from 2015 to 2022. You can use this article to determine a Qualifying Mac as it lists macOS compatibility with various Apple hardware:

https://eshop.macsales.com/guides/Mac_OS_X_Compatibility

Remember, if this laptop has never had macOS 10.13+ installed, then you will not be able to use this NVMe SSD until you install an original Apple OEM SSD and install macOS 10.13+ to it so the laptop's system firmware is updated to work with an NVMe SSD.

setting up any new drive using Disk Utility is a REQUIRED step.

You must ERASE the new device by its immutable manufacturer-assigned device-name (not any human-created name like 'Macintosh HD').

If the device-name is not showing, be sure to use the View Drop-down menu to select 'show all devices'.

Use Internet recovery.

Invoke Disk Utility.

make certain "show all devices" is the current setting

NB>> If your device does not appear in Disk Utility and show its make&model AND a reasonable non-zero size/capacity, it cannot be used in this computer for any purpose.

ERASE the device by its immutable manufacturer device-name.

If you are using an NVMe SSD, then you need to boot into macOS 10.13+ in order to see the NVMe SSD. In fact, you must already have had macOS 10.13+ installed on this laptop at some point in the past since the laptop needs a system firmware update from a macOS 10.13+ installer in order for the laptop to even communicate at a hardware level with an NVMe SSD.

If you are using an M.2 SSD, then you should use a Sintech SSD adapter.

then your equipment line is not correct:

MacBook Pro 13″, macOS 12.5

MacOS 12.5 is Monterrey, which your 2015 MacBook Pro is capable of running.

I think you may have meant MacOS 10.12, Sierra, and advice would have been completely different if Readers (other than the very perceptive HWTech) had realized that.

<supplemental background information>

Where did Recovery HD on the Boot drive go? Why is it so hard to find after 10.12 Sierra?

The HFS+ Extended disk structure is used on the boot drive through 10.12 Sierra, and it leaves Recovery as a separate partition (out in the open) where the ROM-based Startup Manager (aka Boot Picker) can always find it. Diskutil disk numbers will change, as they are re-derived at boot time. Diskutil list output can look like this:

/dev/disk1 (internal, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *80.0 GB disk1

1: EFI ⁨EFI⁩ 209.7 MB disk1s1

2: Apple_HFS X12-Drv80⁩ 79.1 GB disk1s2

3: Apple_Boot ⁨ Recovery HD⁩ 650.0 MB disk1s3

--------

By the time you get to about 10.14 Mojave and later, APFS is firmly entrenched and Recovery HD is no longer a partition, it has disappeared inside an APFS Container, where older ROM-based Startup Manager (left over from the HFS+ Extended age) may not be able to recognize it.

/dev/disk5 (internal, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *240.1 GB disk5

1: EFI ⁨EFI⁩ 209.7 MB disk5s1

2: _APFS ⁨Container disk7⁩ 239.8 GB disk5s2

-AND-

/dev/disk7 (synthesized):

#: TYPE NAME SIZE IDENTIFIER

0: APFS Container Scheme - +239.8 GB disk7

Physical Store disk5s2

1: APFS Volume ⁨ X14-SSD240⁩ 96.7 GB disk7s1

2: APFS Volume ⁨ Preboot⁩ 26.5 MB disk7s2

3: APFS Volume ⁨ Recovery⁩ 507.6 MB disk7s3 no longer a partition, also not tagged as Apple_Boot

4: APFS Volume ⁨ VM⁩ 20.5 KB disk7s4

How exactly did you install the OS onto the drive? You can't simply copy the OS to theh drive if that's what you did.

Are the SSD's you used compatible with your MacBook?

Are they installed correctly into the Macs hardware?

You're welcome.