That was another reason for the RPi4 iSCSI shim (https://scsipub.com/initiators/PI4-iSCSI-shim/) - not over scsipub.com itself if you need performance (latency over WAN) - works "OK" but not great.

You can demo it out on scsipub without having to provision local SAN, and I came up with scsipub idea as a consequence of lack of any public iSCSI hosts to try things out.

Yes, it's ridiculous, but I have plugged my M1 Macbook Air to (LAN based) iSCSI through a Pi4. Works remarkably well.