Ugh.
Pore filling wood.
Always a chore but a necessary chore.
Especially if you’re desiring a flat and level finish.

The most common open pores woods?
Oak, Walnut, Mahogany, Ash, Rosewoods.

If you don’t have specific pore filler, then you can just use spackle from the hardware store and add the pigments you’d like.

Let me know if any questions!