They are competitive for hobbyist use cases. Limited home servers, or embedded applications that overlap with arduino.

I picked up some 1GB Rock-2F boards while available in the US for ~$10/ea. Seems they aren't shipping the 1GB boards to the US anymore though. Before this, I had a couple Raspberry Pis; one I fried, and the other acted as a web server for a few years.

My realization in ordering the Rock-2Fs is I really only need an MMU (that is, an SBC instead of something like an ESP32) when I'm running something with a graphical desktop, which is, outside my workstation, never (except for kiosks, which I use Android tablets for). -OR when I want to plug something into a bloated SBC board which saves me from having to solder a connector on, which is sometimes.

I use one for running a timelapse camera (camera is USB) while another is a portable mp3 player I can put in shirt pocket and which has aux port (tho its aux line is noisy). -So that's two of the four Rock-2F boards in use.... but it took me far less time to think up uses and deploy 25/25 of seeedstudio's ESP32C3 boards I ordered a couple years ago, and have used ~5/25 of the ESP32C6s I ordered early this year. They're so cheap, and use so much less energy than ARM boards, that it's difficult to justify using the SBCs anymore.

I think they're asking $50 for a base 2GB Pi4B, now -- that's 10 ESP32C3 boards (with integrated WiFi and BMS, btw!) -- and the Pi5 is even less competitive except in what I'd characterize as a very unusual scenario where you need high compute at edge (where it's both needed AND the latency of computing at the edge is lower than sending it to central server for processing), OR you need the security of protected memory, OR you have no central server and an ESP32 isn't going to cut it (I'll say, though, that one can run a thermostat with multiple WiFi-connected thermometers, and run a web server interface just fine.).