Sent MacBook Pro M1 Max 2021 with 2TB SSD's in for logic board replacement. They gave me a logic board with 1200 hours on the SSD's. They are telling me S.M.A.R.T. isn't supported. Is this true?

Apple SSDs don't have much SMART health information these days. I always look at the SMART information whenever I'm working on any of my organization's Macs just to keep an eye on them and see how they behave. I have noticed some odd variations in the "Spare Threshold" values on the 2016-2020 Intel Macs, but that is really insignificant. Plus sometimes it appears the value is shown in an inverse manner....should be something like 2%, but sometimes reported as 98%. More than likely those SSDs are from a different manufacturer (Apple procures components from at least two supplier for most items).

I've never seen anything that would suggest to me that the SMART information is inaccurate. I know there was some discussions when the M1 Macs were first released in 2020 about the high amounts of Writes being reported whether it was being misreported by the SSD, or the SMART monitoring software was misinterpreting the values, or whether they M1's were actually writing huge amounts of data (I think it came down to the way the GPU works and it was resolved with a macOS update). I haven't seen any other mention of issues regarding SMART on Apple Silicon Macs in the media.

In fact Apple's service diagnostics still check SMART. Plus on my 2023 M2 laptop even Disk Utility still has a "S.M.A.R.T. status:" item when you click on the physical SSD on the left pane of Disk Utility (the physical drives are now hidden by default).

While disappointing that you received an SSD with much more wear than your original Logic Board, as the others have noted it isn't really significant. But I definitely recommend people check the SMART information of their SSD before service and after service to make sure they are not too far off & to make sure the SSD isn't heavily used or having any problems (I had an integrated SSD fail on a 2017 MBPro within 90 days of an official Apple Logic Board replacement.....that was the one time I didn't check the SSD health after the repair --- the SSD had worn out due to excessive writes....no way that the user had written that much data within 90 days). More than likely the SSD controller will fail first (no health information for the controller) before you wear out the SSD. Back around 2012 a group performed a 24x7 torture test on a bunch of SSDs....most of them survived to write PBs of data before the SSD finally wore out.

https://techreport.com/review/the-ssd-endurance-experiment-theyre-all-dead/

As far as I know, SMART is supported and tools like DriveDx and Smartmontools can correctly read that data including the amount of data written and read from the NVME drives used in modern Macs.

80TB is probably 5-10% of the write resource of the drive, so you still have 90-95% of its resource available.

1200 hours is not a lot but it is clearly not fresh new drive.

For context on price see this comparable drive module offered by Apple (admittedly for Mac Pro):

Apple 2TB SSD Upgrade Kit

As far as I know, SMART is supported and tools like DriveDx and Smartmontools can correctly read that data including the amount of data written and read from the NVME drives used in modern Macs.

80TB is probably 5-10% of the write resource of the drive, so you still have 90-95% of its resource available.

1200 hours is not a lot but it is clearly not fresh new drive.

<< Was told that they would replace the logic board with new or like new parts. >>

Did you present a Mac for service that was new? That had only 5 hours of power-on time? I doubt it.

Apple warranty covers defects in materials or workmanship for the warranty period. Apple will repair or replace at it discretion to return your Mac to a properly working condition.

It does NOT state that the parts used will be new. It essentially says that your computer will be returned to working condition, such that is would be expected to work in a similar way at least through the rest of the warranty period.

What you got was your computer returned to serviceable condition with no defects. That is Apple's only obligation under warranty ro AppleCare PLUS.

If you like, you could request that the agent who gave you wrong information be re-trained.

Here is the language from the warranty. This is used for every repair regardless of who is paying for it.

WHAT WILL APPLE DO IN THE EVENT THE WARRANTY IS BREACHED?

If during the Warranty Period you submit a claim to Apple or an AASP in accordance with this warranty, Apple will, at its option:

(i) repair the Apple Product using new or previously used Apple genuine parts that have been tested and passed Apple functional requirements,

(ii) ...

The way I read that, Apple will provide parts "that FUNCTION as new'.

...That is not the same as "ARE New", or "could be sold as new".

ref:

Legal - Mac Warranty Us - Apple

Took it in and they said we need to replace the logic board.

They? Took to whom? Apple? an Apple Authorized Service Provider? An independent repair shop?

It is hard to answer this question when we have to guess who serviced your device.