If I use what appears to be a 100mh (by comparing it with 100mh coil
images online) and it turns out to be a different value, what will be
its impact on the performance or other factors
You'll probably find that 100 mH is far too much for most applications but, you never said what application it is so maybe it's secret.
I'd try it on a dummy representative load so that there is no chance you'll overstress something that is important. You will need to test it on load because it is the load that soaks up the energy liberated from the inductor. An open-circuit load means energy liberated continues to grow the capacitor voltage until something turns to smoke.
Try an online calculator to test things out: -
If you enter values for Vin, Vout, inductance, load resistance and operating frequency you can see how the inductor current peaks up and whether you will operate in DCM (light loads) or CCM (heavier loads). Try a few different inductor values to see if 100 mH suits your application.