I agree, unlike an OS service pack it's not like a rollup and as such you can pick and choose which firmware etc to install so looking at one particular version on your host won't necessarily indicate the levels of everything else.
That said, if you have a policy to install the SPP wholesale then you could identify one particular piece of firmware or driver and check it against the Contents Report of an SPP release (eg. here)
In vSphere you could check the versions you have on your hosts on the Hardware Status tab, or the HP Insight Management plug-in, or iLO site if you have one to try and determine to what level your firmware etc. is at.
Hope that helps, good luck
vM
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