Aperture will work under virtual machine with Mojave or other older OS. This can be done for free using Virtual Box or a little easier for a fee using VMWare Fusion or Parallels.
Or it will run fine under 64 bit Catalina except for some nonessential features if it’s patched using Retroactive, link below.
“All Aperture features should be available except for playing videos, exporting slideshows, Photo Stream, and iCloud Photo Sharing.“
I’ve been using both these methods for a few weeks.