If you can make the full node run somewhere else then all electrum server choices don't require a lot of resources to run.
So if you have a bitcoin core instance already running like on your personal desktop, you can expose ports on your router and then run the electrum server standalone (assuming you want to run them on different machines, instead of also on the personal desktop) then give the server the ip address and port of Bitcoin Core.
That's funky, point my Raspberry Pi with ElectrumX to my desktop and then point my Electrum on my desktop to my Raspberry Pi :-) But that's not what I want to do. I have Bitcoin Core running on my Pi and I would like to run an electrum server on the same device. Do you think my 8GB Pi 4 can handle ElectrumX + Bitcoin Core?