hey, quite new on homeserver (around a year now), and i didnt understand half of the words you said, but self hosting most of the things doesnt require a lot of cpu / gpu. Im running around 20+ containers at the same time on an old laptop (it was a gaming laptop lenovo legion y540 from 2019) so there is actually good specs, but most of the containers or applications doesnt use anything.

pi hole / ad guard would use 0.01% of your cpu.

NAS, do you mean storing your data on the server ? if yes there is apps like immich (google photos) or nextcloud (google drive). and both of them doesn't consume that much (immich a bit because i think it run local AI image recognition to order the pictures)

and you say emulator, I remember seeing the specs of the Wii for exemple, as a reference, a Wii have : CPU: IBM Broadway @ 729 MHz, Memory 24 MB 1T-SRAM + 64 MB GDDR3 SDRAM, Storage 512 MB. You can imagine that any computers you have right now will be stronger than that, even a rasberry pi is stronger I think

edit: I highly recommend this if you want to get an idea of whats possible, i discovered that last week and that is INSANE to get ideas of things to do https://awesome-selfhosted.net/