No planetary nebula in sky is bright enough to be seen by naked eye (the brightest is Butterfly, at +7,1).
But suppose that a planetary nebula were located really near Sun - a few lightyears or less.
Say, Ring Nebula. Magnitude +9, contains a star magnitude +15,75, at roughly 5000 lightyears distance.
Now imagine the Ring from distance of 5 lightyears. 15 magnitudes brighter. At -6, the Ring would outshine the Milky Way and cast light on moonless night. But if its radius is just 1,3 lightyears, it would still be being viewed from outside. The central star, at +0.75, would be a prominent star but dimmer than Toliman at the same distance.
How much of the structure of the nebula would be visible for an observer at a few radii?
And what would the nebula look like for an observer actually inside the nebula? Say, the Sun at 1 lightyear from the nebula? The central star should be -2,75, outshining all stars and planets save Venus, but how does the nebula look like inside?