Do the M1s have especially short write lifetimes? I have a Toshiba from 2010 or so and the SSD is still fine even if the trackpad and speaker ports died years ago.

In 2013, TechReport did an SSD endurance test: for months, it ran non-stop write operations, a much more strenuous use case than what a regular laptop would experience, which will be primarily read operations. 4 months in, after writing 300TB, all the tested devices were still working without issue.

If the characteristics of the SSD in an M1 are sufficiently similar to the SSDs that were used back then (I have no clue if that's the case), wear out will be a non-issue.

Since 2013 there have been multiple iterations of SSD technology that increased storage density but sacrificed storage durability: https://www.howtogeek.com/444787/multi-layer-ssds-what-are-s...

This is why people are concerned about SSD endurance. An old SLC SSD's NAND would be good for many, many writes, tho the controller would often fail. Nowadays the NAND fails, but the controller is fine.

I'd note that the 2013 MBP also has an SSD that hasn't experienced any problems so far.

After 2 years of use, my M1 MBP has 5% write life used. Extrapolate that out and you get 40 years of lifespan.