I too, after Apple removed support for connecting to APFS computers from older Macs, just opted to send files to my local server from my newer machines, and view them on the server on the older ones. I have a 2006 Mac Mini with gigabit ethernet running Snow Leopard Server for that task, and it has a public folder for files, apps, and other stuff I want on my older computers, and I usually just plop them in there from my M2 MacBook Air nowadays for ease of downloading, but then my PowerPCs and early Intel Macs can see the shares on the Mac Mini just fine. The server also holds my Time Machine backups for my MacBook and a few other computers in the house, for wireless backups to a large external USB drive.