how to make a bigsur installer on a new macbook pro m1

To perform this action will require booting from a Bootable Installer. 

The Bootable Installer can Only be performed on an Apple Computer 

This will have to be performed from a Qualifying Computer to run the version of macOS to be made on the Bootable Installer.

Example : Bootable Installer of Big Sur would have to be done on a computer that Qualifies to run Big Sur.

Notation: If the computer being used to perform this action is Too New or Too Old to qualify to run the version of macOS - this computer can not be used.

Alternative is, to gain access to a Qualifying Apple Computer from a family member, friend or associate.

Big Sur will only install on:

MacBook Air (2013 or later) [Machine ID 6,1 shipped with 10.8.4, has to be upgraded to Mavericks 10.9 first

if you saved it in your App Store, or 10.12 from the App Store & have 35 GB free after the upgrade first before installing Big Sur.]

MacBook (2015 or later) [Machine ID 8,1 shipped with 10.10.2]

MacBook Pro (Late 2013 or later) [Machine 11,1 shipped with 10.9]

Mac mini (2014 or later) [Machine ID 7,1 shipped 10.9]

iMac (2014 or later) [Machine ID 14,4 shipped with 10.9.3]

iMac Pro (2017 or later) [Machine ID 1,1 shipped with 10.13.2]

Mac Pro (2013 or later) [Machine ID 9,1 shipped with 10.9.1]

Up to Monterey's 2021 release date of October 25, 2021. Newer Macs won't run Big Sur or its installer.

If the Mac was released after November 12, 2020, use the internet restore command load Big Sur on the Mac if restore doesn't work. Keep in mind if you already installed Monterey on the Mac, only completely erasing or partitioning the machine will allow you to restore an older system, since libraries designated for Monterey are typically incompatible with Big Sur:

How to reinstall macOS - Apple Support

That's where having an older clone can help.

Does this Terminal command show Big Sur:

softwareupdate --list-full-installers

If not, then it seems your MBP needs at least Monterey.

If that is the case, download Big Sur in Mac Pro, or boot it to Internet Recovery mode to do the install.