Moving Aperture libraries from 2009 iMac

Hello, TIA for any assistance with this, quite specific and personal question -

I'm looking to move a few saved Aperture libraries (which are backed up to an external Time Machine drive) from my (sadly passed away) father's late 2009 iMac running High Sierra 10.13.6 with a 1Tb upgraded internal SSD.

He was a photographer, and from what I can tell imported photos directly into Aperture. He has several libraries - all as consolidated 'package' files (each around 100gb on average) - for different projects. Each library is organised with folders of sub-categories etc.

I have just purchased a Mac Mini M2 256gb base spec to transfer/upgrade this iMac for my mum to use and continue his legacy with access to the photos for printing, possibly editing etc. I plan to set up the new Mac a-fresh rather than restoring from Time Machine or using Data Migration, simply so I can manage what is transferred and keep things running smoothly. I know it is going to laborious as there's a lot of files to sift through on the current iMac.

The goal is to keep everything as-is as much as possible with what is in Aperture. So file structure/project organisation, edits, originals etc. There isn't going to be enough room on the Mac Mini for libraries to be stored on there so looking to keep them on an external "project" drive (and then probably have multiple time machine drives for multiple backups for the m2 mac mini disk image and the "project" drive). Quite open to recommendations for what application to use on new Mac for photo management/editing, but looking at using Lightroom.

Ultimately, we don't want to lose any of his edited photos, or in fact any of the photos at all, and the filing system. My current thinking is to purchase a couple of new external drives and go about opening each Aperture library, one at a time, and exporting originals (perhaps into manually created File Folders in Finder with corresponding 'project/folder' names) and also exporting 'versions' so the edited ones are saved too, onto a new external drive. Then when the new Mac is setup, installing Lightroom or whatever, and opening the photos (hopefully with the project organisation/folder hierarchy) there, from the external "project" drive.

Very much a newbie to Aperture/photography data so after quite a lot of research just thought I would put the question here. Unsure about things like 'Metadata list, IPTC4XMP Sidecar Files' etc, but as I say, it's about preserving everything first and foremost, and being able to view photos on new machine.