Migrating from Aperture to Photos - do with High Sierra machine first, or wait to do with Monterey M1?

You definitely need to migrate the Aperture Libraries while you are still having a system version installed, that supports Aperture. When you open an Aperture Library in Photos, it will create a new library from the Aperture Library. This new library may need some work to recreate the slideshow project, the smart albums, fix some metadata like the dates or locations, or you may need to identify videos and photos in a format, that cannot be processed any longer on Monterey and need converting while still running High Sierra or Mojave. Only on your old mac you will be able to open both Aperture and Photos at the same time and to compare the two libraries.

Before you upgrade to Big Sur you need t9 ensure, that all edited items in the Aperture library are having high resolution previews. The reason for this is, that the adjustment will be transferred as previews of the adjusted version. If you do not render previews while yiy still can rub Aperture, you will lose the Aperture edits.

Aperture won't play nice with macOS Catalina or newer, including macOS Monterey, so you should migrate your library on your Mac with macOS High Sierra.

Migrate your Aperture library to the Photos app or Adobe Lightroom Classic – Apple Support (UK)

Once you've migrated your library, you can use Migration Assistant to transfer your files from your old device to your new MacBook Pro.

Move your content to a new Mac - Apple Support

You can also use other apps to edit photos instead of, or alongside, Photos, like Adobe Lightroom, Adobe Lightroom Classic, Affinity Photo, or Pixelmator Pro.

As bumbleben says, yes, migrate first.

However: remember that Photos is a giveaway app and is nothing like as capable as Aperture was.

Also:

You can also use other apps to edit photos instead of, or alongside, Photos, like Adobe Lightroom, Adobe Lightroom Classic, Affinity Photo, or Pixelmator Pro.

In the case of Lightroom and Lightroom Classic, these are, like Photos and Aperture, parametric editors. They can only operate on images in their databases, and can only share these images by sharing them. In other words, all Photos, LRC and LR are all photo managers, and using three photo manages makes as much sense as three address books. If you want an app as capable as Aperture (and more) then Lightroom Classic is what you should use. If you want a more powerful app than Photos, Lightroom is what you might consider.