So.... are these holes and piles of dust caused by something? ....flying things walking things wriggly things.... going in or coming out ?
As Jacob indicated, they're exit holes, and most likely those of the now mature and flying common furniture beetle or
anobium punctatum. They emerge and look to mate and lay eggs in crevices in the wood (coarse grain, cracks, splits, etc) or intersections where two pieces of wood meet, e.g., somewhat gappy shoulder lines of M&Ts, end so on. Furniture beetle likes oak sapwood because it's nutritious, and less fond of heartwood because it's less nutritious, but given time the beetles will tunnel voraciously in both wood types.
It's likely there are still a number of less mature beetles burrowing away in the wood so repeated treatment with furniture beetle killer would be advisable over the following two, three or four years. The treatment doesn't kill the beetles because it's topical, and they're well below the wood surface, but it affects the emerging adult as it chews through the treated upper millimetre or so of the wood and the ingested chemicals harm the adult, and if harmed enough it dies and therefore has a reduced chance of reproducing.
It's reckoned that wood at or below 12%MC is an especially difficult environment in which the common furniture beetle can survive so, assuming your furniture is now at or below that moisture content, it's likely the problem will diminish over a year or two and then stop, especially if you undertake treatment. My experience of furniture in habitable buildings, i.e., it's dry at around 12%MC or below is that common furniture beetle infestation or reinfestation is highly unlikely. On the other hand I've come across examples of furniture stored in relatively damp locations for fairly long periods, in such as outhouses, sheds, damp(ish) furniture repositories and the like, that have become infected.
I suspect the infection, or perhaps repeated infestations, happened prior to you building the piece when the wood was wetter; perhaps it was only air dried and didn't get a higher heat treatment that kilning would induce which would have gone a long way towards killing any existing grubs in the wood. An alternative might be that the wood was kilned and subsequently was stored in conditions that were moist enough (atmospheric relative humidity plus wood moisture gain) that made it attractive to the adult beetle. All the previous in this paragraph is pure guesswork or speculation as I have no idea of the wood's history. Slainte.
