If it's not a base-model. If you're one of the unlucky shmucks running an 8/256 M1 Macbook Pro, you'll be lucky to get $500 for it on the secondhand market.
Swappa shows that you can get much more. The current average sale price for a Macbook Air, M1, 256GB is $673 respectively. Compared to the $1000 MSRP you're getting about 67% back.
Note that Swappa takes a 3% cut, so the buyer would actually see around ~$650.
It gets even better. I got my M1 Airs (base model) for like $850 arg (two at $950, 2 at $750 - all brand new).
They're still great little machines - like my still-running 2010 Air (so retro I keep it around for kicks) - I expect these to last pretty much forever.
Great for the kids/elderly when configured properly. Minimal support effort. My kids treat them like their Nintendos and they just work.