I wanted to say thank you and close out this thread. With your help, I've managed to get all of the precious memories and files and critical data off of my brother's old server and onto the new one. So thank you is not enough, but I do want to say it...and thank you from his wife and kids, too. For anyone who might be in the same situation, here's what I did. It's probably not the best way, but it is a way that a beginner could move data and VM's from Proxmox to a new server like a Synology NAS. (Note: first you have to be able to see the proxmox server via a web browser on your network--so watch a video on how to setup proxmox to learn about that part if needed.)
1. Setup an NFS connection from Proxmox to the new NAS device over the network so that each container and VM can be backed up directly to the new NAS from Proxmox. Here's a youtube video that helped me with that:
https://youtu.be/ZSBcZSC6fJI.
2. Back up each one. Now you'll have all the VMs backed up and in a zip file on the new NAS. There was one that was too big to backup, and I think it's the one that had all the data in it. So I needed a different way to copy this data over.
3. Once I setup Winscp, I could see the files on the Proxmox server. I found a folder called 'content'. It was in one of the directories off of the root directory that was called my-zfs-pool. I'm not sure if that is a standard folder, but that's what this one was called. I noticed that it's also what one of the storage containers was named. That's where I found ALL of the native data that held personal photos, video, and family files and memories.
4. From the new NAS, I could setup a mounted drive using SFTP that mapped from my-zfs-pool to the new NAS in a folder that I created. This information helped me, but I had to use SFTP because CIFS/NFS didn't work for me:
https://kb.synology.com/en-ph/DSM/help/FileStation/mountremotevolume?version=7. Be sure you use the root user and password.
5. Now that I have all of the data copied over and all of the VM's and containers backed up, I plan to create a new proxmox server from a USB drive on my Windows PC so that I can bring up each one, back up the configuration of each, and then restore it in the new NAS using the 'best practice' for running that application on my new NAS. In some cases, that's a docker container or in others it's a Virtual Machine or in others there's a native app available from the Community. That part I'll have to figure out, but it's nothing mission-critical in my case.
Everything I did was from a graphical user interface (gui); so, I didn't have to use advanced commands or anything (thankfully). Thanks again to the community here and all who took the time to help me.