Don't use any acrylic, alkyd acrylic water based stains prior to any epoxy work. They are basically acrylic paint watered down and will seal the grain.
The best is alcohol based stains (dye) for wood. You could use artist watercolor paint which has no acrylic (plastics) in it but its not very light fast (can fade out with the UV).

In furniture making, woodworkers used to bleach wood to lighten it for effects but it became unpopular because you can get some terrible surprises. It was a two part bleach. You wet the surface with one chemical and let it soak and then add another. Then wash it down and pray.

Stain vs. dye? A long time ago stains were made from natural products like earth, ground stone, berries etc. A dye is made by mixing chemicals - usually liquid together and it turns a color.
Stains are usually water based or turpentine based and oil which resists epoxy adhesion.