Yep, I realize that Doctor Spectrum was created to be Marvel's homage to the Green Lantern, just as his teammates in the Squadron Supreme/Sinister are Marvel's Justice League. But I don't ever recall Doctor Spectrum mentioning that he got his power prism from nigh-omnipotent Guardians-type beings who championed life and law (as distinct from morality) throughout the multiverse. If I'm not mistaken, the prism may have been given to one of the Spectrums by the Skrull Skymaster (the analog to Martian Manhunter), but that's not quite the same thing as what we see with the Guardians.
I imagine that was by design as DC might have pushed back on the homage being too close to the real thing. Still, for my money, I would like to see Marvel dance the tightrope a bit more closely by introducing someone like the all-powerful
Queen of Nevers as the guiding force behind the Power Prisms and the Spectrum Corps. After all, if memory serves, she was the being that restored and supported "the many-colored ones," i.e., the Celestials, in the Eternity War. That epithet -- the many-colored ones -- seems like a veiled callback to the emotional colored spectrum of the lantern rings. Or am I reading too much into that?
All that said, if the Nova Corps are Marvel's official space police force, so be it. Not my preferred choice, but let's go with it. Just have to get used to drawing buckets on heads, I guess.