The NG FPV has a purely inertial mode and more importantly can still be displayed even if both ADRs are 'TU'. It can function and be useful with only the IRUs to drive it. Naturally whether you use it or not is up to you. Follow your FCOM of course.
Interesting, can you point me to the way to switch it to that mode? In the normal mode it relies on ADC inputs for the vertical part of its display. It can be displayed without that, but is unreliable in that case, which is why boeing removed a note to use it from the unreliable airspeed NNC after they discovered that it can show in fact very misleading information. We had a few cases where the FPV was used in an airspeed unreliable scenario (caused by frozen AoA vanes which also invalidates altitude and GS as well as wind display) in the real world and if followed would have lead to loss of control. Basic pitch and power was of course the way to go and ultimately saved the day.
If you mean with "AoA" information the pitch limit indication which is displayed with flaps deployed or activated stick shaker, those are not pure AoA driven either, they do take inputs from the AoA vane (no surprise there), ADIRU outputs (both IR and AD part), anti-ice controls, wing configuration, thrust and FMC outputs. Quite a lot of information mixed together and computed by the SMYD computers.
I would be very cautious about simulator trials for that stuff, many level D simulators are not very good at correctly simulating some of the things that are not used with standard boeing SOPs, like for example the edge of envelope behavior of the FPV.