You'd be correct, no ECU relay on these 3rd Gens. I attached a wiring diagram reference for you, I imagine they are referring to the EFI relay. What I would do personally is bypass the EFI relay by using 2 spade connectors connected with a wire to act as a jumper, and jump the 2 larger EFI relay pins to test that. You would be correct about the NSS causing a no crank, but you can bypass that as well and eliminate that as a cause pretty easily. I attached a picture of the pins that I would jumper together, you would unplug the NSS connector and jump them on the connector itself. Theres also a continuity test you can do for the switch itself to eliminate that as a concern. Only reason I bring that up is the fault code specifically for the PNP/NSS (Park/Neutral Position Switch / Neutral Safety Switch, same thing AFAIK)
I would also check whether the GAUGE fuse is getting power from the IG1 switch, easy way to check is to key on car off, press cruise control switch and see if the light comes on. If yes then IG1 is powered, if no then trace back the FSM wiring diagram from there. Also, check if the ABS/Trac/etc lights come on and stay on with the key in various positions, could get some useful info from that.
Also, check all your fuses with a trusted meter for continuty, since a good deal of them can cause a no start issue, great resource if you've never used it is:
2002 Toyota 4Runner fuse box diagram - StartMyCar
Has a detailed diagram for each fuse plus brief descriptions. Main ones Id really check are EFI, visually check or remove and test the all JCASE style fuses, speficially AM1/AM2, OBD fuse, ETCS, STA, IGN, ECU-IG.
Good luck and keep us posted!