I'm looking for something with a simple GUI

If you do find (or build one) let me know. I'm interested myself. Well, not sure if it counts but you can run Amber in an Android emulator (that's what I used to do before modifying nak)

Ah yes, the non-technical option, running Amber in an emulator

Amber is undefeated though

It can be annoying to setup, but nowadays you can have a desktop icon that loads it in full screen. It is a bit slow to load and resource intensive but not at all unfriendly to normies once someone takes care of the setup (or build a nice installer). Not adequate for normies, but out of the options I found a few months ago this is what I would set on my parents computer if I ever wanted them to use Nostr :).