It would make sense if you’re using your main machine to test the waters with to see if it’s worth getting invested.
So your pihole as an example would work as follows:
With the primary DNS being a “local”, I can’t imagine it taking that long to realize it’s offline and change to the secondary DNS on most devices. Make sure you set your “main machine” to a Static/DHCP Reserved IP on the home router, as a good general practice.
Other things I self-host are media related. I like to watch media from bed instead of in front of the computer. I turn my computer off when I’m not at it.
I could see if you were like hosting a local repository maybe. Like you want that whole “self-hosted” GitHub experience. That would be a decent use case for main machine hosting. Or VMs for testing different environments.
Laughs in kitten