Would it be fun? Probably. Would you learn stuff? Almost certainly yes. Useful as a full time production environment? Nah.

There are worse things to spend your money on. If it all goes tits up, usb network adapters are always useful, especially with the amount of laptops that don't come with network ports these days.

I got a 6 node "cluster" set up following this guide on the one computer.

If its just files over NFS its more than likely fine. If its a database of some sort, it might work up until it doesn't, as I found out recently. My Uptime-Kuma DB got corrupted and I had to redo it from scratch. They also say NFS mounts are unsupported so that's what I get.

Synology DS1821+. I had a go at making a hyperconverged setup with an HPE DL380p G8, loud and power hungry. Also HPE are dicks with their hardware, can't boot off the array when in passthrough mode.

Got a SuperMicro machine to try the same thing, again, loud and hungry.

The Synology is quiet and sips power. While it has no hope in hell of doing ZFS and the interface is proprietary as hell, SHR2 and BTRFS just works for me. I have a large network accessible space for "linux isos" and iSCSI for Proxmox.

I need to get rid of those 2 servers...

Uptime-Kuma has push monitoring. Get the modem or another device connected to it to curl or wget the URL every minute then have Uptime-Kuma send a Discord or Slack or whatever notification to you. When the url becomes unavailable, you get a notification.

Host it on a VPS or you can use Fly.io for free.

LPT: if you store your data on a NAS or somesuch, you can use NFS volumes to expose that data to your containers. That way, if you need to rejigger or blow away your setup, you don't lose anything that can't be rebuilt easily.

Get a Synology or Qnap device and install Tailscale or Zerotier.

Can you dump the output of docker compose logs adguardhome?