This appears to be the first cheap(ish) Mac with replaceable storage in over 10 years.<p>The manual clearly shows how the SSDs are removable and that the module is different between the M4 and M4 Pro versions.
Exploded view and orderable parts are shown here:<p><a href="https://support.apple.com/en-us/121008" rel="nofollow">https://support.apple.com/en-us/121008</a>