Self-Hosted Main

Your DE won't use that much cpu no matter which you use.

As long as you want to run out of ram you should be fine.

But imo it's a bad idea to mix a server os with a normal desktop use.

How about using proxmox and having a vm just for desktop use, like this you could also just pause all the resources easily when you're not using your desktop computer. Personally i would have a debian stable and a proxomx vm and just enable the proxmox vm whenever I need it.

If your not scared of scripting you could also unsuspend the vm via a keyboard listener. (for example trigger unsuspend when key f3 is pressed. This would be doable with evtest and qm resume )

Or if you don't want to use a vm you could also disable the autostart of the DE and start it via shell when you really need it.

I run proxmox on my optiplex with a 3rd gen i5 (dont remember actual name) and 16gb of ddr3. I have truenas, HA, docker and pihole on it, but i dont run it heavily as its just for playing around. Its run smoothly tho.

I don't understand what you mean with "does decreases the hardware usage in some idle time"?

I also don't understand what "overloading" Pop means.

Light virtualization and a few services - and sometimes also your desktop, when needed - shouldn't be a problem, but it also depends on which services and how many.

In general, containerization is easier than virtualization, and has less overhead. If you want to stick with Pop, then you can install docker, docker-compose and portainer. Portainer provides a pretty decent web interface to create and manage containers.

You can make VMs possible by adding cockpit and cockpit-machines, so that you can create and manage VMs (I'm guessing that cockpit is available for Pop).

Otherwise Proxmox is a free hypervisor, based on Debian and pretty easy to learn, and then you could have one VM for your self-hosted stuff, and one VM, with Pop on it, to use as your desktop. Turn off when it's not needed, turn on when it is.

From there, you can build out your homelab in a somewhat modular fashion, which will also mean that modifications will be less likely to break something, and easier to undo or fix.

Debian

Have you heard of UnRaid?

I run two daily driver / gaming VMs simultaneously on one CPU and motherboard with two GPUs. Then I have services running on UnRaid's built-in Docker (Plex, Home Assistant, file/photo "cloud," etc). Though I'm reconfiguring my setup to be more services based and less dedicated to VMs.

For example, I have Blender running as a service (Docker container) that I can access via web browser on any device (including my smart tv, just because I could).

You can choose to either "pin" (exclusively dedicate) resources to some things or let them be dynamically shared. There's caveats with that when it comes to passing hardware through to VMs (mainly GPUs).

Unraid

I would actually install a classic server linux without GUI. But you might install cockpit for having a nice webui to manage your server. Thats much more resourceefficient

Install a hypervisor.

Install best desktop OS in one VM.

Install best Server OS in another.