With any coating, the prep is key, so if you are applying yourself, there are a lot of youtube videos to help get an idea before you order a bottle and DIY :) Good luck!
I mean i guess best bet now is to get a price of blending vs painting the whole bumper and seeing if the premium is worth it. I have seen some very bad blending, but on my other car, i cant see the blend at all. so garage dependant ! But i will be wary :)
sealants and waxes just cover it up. it will come back after a few washes. Polish the scratches out, then apply a coating which will protect the paint underneath. a coating is ceramic, whilst making your car look better it is also a lot thicker than wax and sealants.
If it catches nail, it can be made to look better, but very hard to get out without removing too much paint. If it doesnt catch the nail, wet sand, compound and polish will do.
Its my go to, having tried many over the years. its not difficult to apply, just apply sparingly. It last a long time vs other waxes too. The light and dark has no difference, just a marketing tool.