I have quite a few pieces colored with transtint dye that have not faded. I did my home computer desk ~ 10 years ago, just as bright now, as are the turnings I have done. Mine are shielded from the sun, but do get some indirect sunlight.
As for "pop the grain" - this tends to be confusing terminology, to me anyway. Sometimes people mean blotching, i.e. color variation across the surface due to varying amounts of liquid absorption by varying grain type, as I think is the case here, but sometimes chatoyance, or the "tiger or cat's eye" effect, is referred to as "grain pop".
I use a couple of different methods to achieve levels of both blotching and chatoyance. If I plan to use a fully filled hi gloss "piano" finish, I use transtint dyes. Many times I use a dark color 1st and sand a lot off, as described above, then add a lighter color, then topcoat. Many times a toner coat is used to bring out intensity of the lighter color. Pic below is not great but shows the color variation and hi gloss. I may one day figure out how to post a video which shows the chatoyance much better.
For a more subdued , lower gloss finish with usually a single more muted color, I use semi gloss MW poly thinned 1:1 with ms, and add WD Lockwood oil based dye to the poly before application. It is applied like danish oil, 2-4 coats, possibly wet sanded, then buffed. The example below was done using just a bit of the dye component of MW Dark Walnut stain to bring out the grain of the maple.