That’s a lot of Linux ISOs.

Supermicro and ASRock Rack both make standard form-factor mini-ITX and micro-ATX server-class motherboards with dedicated IPMI ports that would fit in a shallow-depth rack-mounted chassis.

My thoughts on buying a system with proprietary components…

Pros

1. Buying typically is cheaper than building.
2. Saves the effort of matching hardware when DIYing.

Cons

1. Requires searching eBay (or other marketplace) for compatible proprietary hardware when a component fails.
2. Some proprietary systems (looking at you hp) can be picky with some replacement components like RAM.

…which for me is uptil 192.168.1.1 - 192.168.1.253 (I cannot edit this, it’s an ISP router)

Are you certain that you cannot set the DHCP range on your ISP’s router? I suggest researching this option a bit further, including contacting your ISP tech support. I have never heard of an ISP-provided router not allowing customers to change the DHC range.

Other options include:

1. disabling the DHCP server on your ISP-provided router and enabling the DHCP server on your Pi-hole with a limited DHCP range as needed, or
2. replace the ISP-provided router with your own router, which could save money if the ISP charges a monthly rental fee.

Single host - Just Docker run + Portainer - Also using Macvlans so most containers have hostnames and static IPs on my LAN. K8s is cool, but I have no need for container orchestration.

Choosing a service to NOT selfhost is a subjective descision.

I host 18 Proxmox VMs and 20 Docker containers at home. I also was selfhosting a WebDAV server for synchronizing my Joplin notes between devices and Vaultwarden for managing my Bitwarden vault, but decided to push the Joplin synchronization target to Dropbox [free] and to use Bitwarden’s free cloud solution for my passwords and secure notes. I did this because I will need immediate access to these two critical sources of information should my house burn down, or get blown over by a tornado. I have extremely strong passcodes for these and trust the hosts.

This was strictly a personal decision. YMMV.

OP, your poll needs an “All of the above” option. That would be my choice.